Strings MCQs in C Language

Strings MCQs in C Language

1.

Output:

#include <stdio.h>
int main() {
    char str[5] = "CABC";
    printf("%c", str[4]);
}

A) C
B) Null character (\0)
C) A
D) Compiler error

✅ Answer: B
Explanation:
C strings are null-terminated → str[4] = \0.

---

2.

Which of the following is invalid?

A) char str[] = "GATE";
B) char str[5] = "CABC";
C) char str[3] = "CABC";
D) char str[6] = "HELLO";

✅ Answer: C
Explanation:
Array size too small → string + null character won’t fit → invalid.

---

3.

Output:

#include <stdio.h>
int main() {
    char str[] = "GATE";
    printf("%c", str[2]);
}

A) G
B) A
C) T
D) E

✅ Answer: C
Explanation:
str[2] → third character → T.

---

4.

Which function is used to find the length of a string?

A) strlen()
B) strsize()
C) sizeof()
D) strlength()

✅ Answer: A
Explanation:
strlen() returns number of characters excluding null character.

---

5.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[] = "CABC";
    char str2[] = "CABC";
    printf("%d", strcmp(str1, str2));
}

A) 0
B) 1
C) -1
D) Garbage

✅ Answer: A
Explanation:
strcmp() returns 0 when strings are equal.

---

6.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "C";
    char str2[] = "ABC";
    strcpy(str1, str2);
    printf("%s", str1);
}

A) C
B) ABC
C) AB
D) Compiler error

✅ Answer: B
Explanation:
strcpy() copies source to destination → str1 = “ABC”.

---

7.

Which function concatenates two strings?

A) stradd()
B) strcat()
C) strmerge()
D) strappend()

✅ Answer: B
Explanation:
strcat(dest, src) appends src at end of dest.

---

8.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str[10] = "GATE";
    printf("%lu", strlen(str));
}

A) 3
B) 4
C) 5
D) 6

✅ Answer: B
Explanation:
“GATE” → 4 characters (null not counted).

---

9.

Output:

#include <stdio.h>
int main() {
    char str[10] = "CABC";
    str[2] = 'X';
    printf("%s", str);
}

A) CAXC
B) CABC
C) CXBC
D) Compiler error

✅ Answer: C
Explanation:
str[2] modified → C (0) A (1) X (2) C (3) → “CXBC”.

---

10.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "GAT";
    char str2[] = "EG";
    strcat(str1, str2);
    printf("%s", str1);
}

A) GATE
B) GATG
C) GATEG
D) Compiler error

✅ Answer: A
Explanation:
strcat() appends str2 → str1 = “GATEG” (Correction: careful: str1 = “GAT” + “EG” → “GATEG”).

✅ Corrected Answer: C

---

11.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "CABC";
    char str2[10];
    strcpy(str2, str1);
    printf("%s", str2);
}

A) CABC
B) CAB
C) ABC
D) Compiler error

✅ Answer: A
Explanation:
strcpy() copies str1 → str2 = “CABC”.

---

12.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[] = "CABC";
    char str2[] = "CABC";
    printf("%d", strcmp(str1, "CAB"));
}

A) 0
B) Positive number
C) Negative number
D) Compiler error

✅ Answer: B
Explanation:
str1 > “CAB” → strcmp returns positive value.

---

13.

Which of the following is a correct string declaration?

A) char str[] = 'CABC';
B) char str[] = "CABC";
C) char str[4] = "CABC";
D) char str[3] = "CABC";

✅ Answer: B
Explanation:
Strings must use double quotes → option B is correct.

---

14.

Output:

#include <stdio.h>
int main() {
    char str[5] = "ABCD";
    printf("%c", str[4]);
}

A) D
B) Null character
C) C
D) Compiler error

✅ Answer: B
Explanation:
str[4] = ‘\0’ → null character.

---

15.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str[] = "GATE";
    printf("%c", str[strlen(str)-1]);
}

A) G
B) A
C) T
D) E

✅ Answer: D
Explanation:
strlen(str) = 4 → last index = 3 → str[3] = E.

---

16.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "GAT";
    char str2[] = "EG";
    strcat(str1, str2);
    printf("%s", str1);
}

A) GAT
B) GATEG
C) GATE
D) Compiler error

✅ Answer: B
Explanation:
str1 = “GAT” + “EG” → “GATEG”.

---

17.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str[] = "GATE";
    printf("%d", strlen(str)+1);
}

A) 4
B) 5
C) 6
D) 3

✅ Answer: B
Explanation:
strlen(str) = 4 → +1 for null character → 5.

---

18.

Which function compares two strings?

A) strcompare()
B) strcmp()
C) strcmpi()
D) streq()

✅ Answer: B
Explanation:
strcmp() → compares strings, returns 0 if equal.

---

19.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str[10] = "CABC";
    str[0] = 'X';
    printf("%s", str);
}

A) XABC
B) CABC
C) XXBC
D) Compiler error

✅ Answer: A
Explanation:
First character replaced → “XABC”.

---

20.

Which of the following is true about C strings?

A) Always end with null character \0
B) Can store multiple types
C) Can be directly compared using ==
D) Cannot be passed to functions

✅ Answer: A
Explanation:
C strings are null-terminated → \0.

21.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "GAT";
    char str2[10] = "EG";
    strcat(str1, str2);
    printf("%c", str1[3]);
}

A) G
B) E
C) T
D) Compiler error

✅ Answer: B
Explanation:
str1 becomes “GATEG” → str1[3] = ‘E’.

---

22.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str[] = "GATE";
    printf("%lu", sizeof(str));
}

A) 4
B) 5
C) 6
D) 0

✅ Answer: B
Explanation:
sizeof(str) includes null character → 5 bytes.

---

23.

Which function copies string with limit on characters?

A) strcpy()
B) strncpy()
C) strcat()
D) strncat()

✅ Answer: B
Explanation:
strncpy(dest, src, n) → copies at most n characters.

---

24.

Output:

#include <stdio.h>
int main() {
    char str[] = "GATE";
    str[0] = 'C';
    printf("%s", str);
}

A) CATE
B) GATE
C) CATEG
D) Compiler error

✅ Answer: A
Explanation:
First character replaced → “CATE”.

---

25.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "ABC";
    char str2[] = "DEF";
    strcpy(str1, str2);
    printf("%s", str1);
}

A) ABC
B) DEF
C) ABDEF
D) Compiler error

✅ Answer: B
Explanation:
str2 copied to str1 → str1 = “DEF”.

---

26.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[] = "ABC";
    char str2[] = "ABCD";
    printf("%d", strcmp(str1, str2));
}

A) 0
B) Negative number
C) Positive number
D) Compiler error

✅ Answer: B
Explanation:
str1 < str2 → strcmp returns negative.

---

27.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str[10] = "CABC";
    printf("%c", str[strlen(str)]);
}

A) C
B) Null character (\0)
C) A
D) Compiler error

✅ Answer: B
Explanation:
str[strlen(str)] → null character.

---

28.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "ABC";
    char str2[10] = "XYZ";
    strncat(str1, str2, 2);
    printf("%s", str1);
}

A) ABC
B) ABCXY
C) ABCXYZ
D) Compiler error

✅ Answer: B
Explanation:
strncat() appends only first 2 characters → ABC + XY → ABCXY.

---

29.

Output:

#include <stdio.h>
int main() {
    char str[] = "GATE";
    printf("%c", *(str+1));
}

A) G
B) A
C) T
D) E

✅ Answer: B
Explanation:
Pointer arithmetic → *(str+1) → second character → ‘A’.

---

30.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "C";
    char str2[] = "ABC";
    strcpy(str1, str2);
    printf("%lu", strlen(str1));
}

A) 1
B) 3
C) 4
D) Compiler error

✅ Answer: B
Explanation:
str1 copied → str1 = “ABC” → length = 3.

---

31.

Which statement is true about strings in C?

A) Strings are null-terminated
B) Strings can contain integers directly
C) Strings cannot be passed to functions
D) Strings cannot be modified

✅ Answer: A
Explanation:
All C strings end with \0.

---

32.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[] = "ABC";
    char str2[] = "abc";
    printf("%d", strcmp(str1, str2));
}

A) 0
B) Negative number
C) Positive number
D) Compiler error

✅ Answer: B
Explanation:
Uppercase ‘A’ < lowercase ‘a’ → strcmp returns negative.

---

33.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "GATE";
    char str2[10];
    strcpy(str2, str1);
    str2[0] = 'C';
    printf("%s %s", str1, str2);
}

A) GATE GATE
B) CATE CATE
C) GATE CATE
D) Compiler error

✅ Answer: C
Explanation:
str1 unchanged → “GATE”, str2 modified → “CATE”.

---

34.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str[] = "GATE";
    printf("%d", sizeof(str));
}

A) 4
B) 5
C) 6
D) Compiler error

✅ Answer: B
Explanation:
sizeof includes null → 5 bytes.

---

35.

Which function compares strings ignoring case?

A) strcmp()
B) strcmpi() / strcasecmp()
C) strncat()
D) strncpy()

✅ Answer: B
Explanation:
strcasecmp() compares strings ignoring case (POSIX). Some compilers use strcmpi().

---

36.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "ABC";
    char str2[] = "DEF";
    strcat(str1, str2);
    printf("%s", str1);
}

A) ABC
B) DEF
C) ABCDEF
D) Compiler error

✅ Answer: C
Explanation:
strcat() appends str2 → str1 = “ABCDEF”.

---

37.

Output:

#include <stdio.h>
int main() {
    char str[] = "CABC";
    printf("%c", str[0]);
}

A) C
B) A
C) B
D) Compiler error

✅ Answer: A
Explanation:
str[0] → first character → ‘C’.

---

38.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "ABC";
    char str2[10] = "ABC";
    printf("%d", strcmp(str1, str2));
}

A) 0
B) 1
C) -1
D) Compiler error

✅ Answer: A
Explanation:
Strings are equal → strcmp returns 0.

---

39.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str[] = "GATE";
    str[4] = 'X';
    printf("%s", str);
}

A) GATEX
B) GATE
C) Compiler error
D) GAEX

✅ Answer: A
Explanation:
str[4] originally null → overwritten with ‘X’ → prints “GATEX” (undefined behavior if null is not at end).

---

40.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "GAT";
    char str2[] = "EG";
    strncat(str1, str2, 1);
    printf("%s", str1);
}

A) GAT
B) GATE
C) GATEG
D) GATE

✅ Answer: B
Explanation:
strncat appends first character of str2 → GAT + E → GATE.

41.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str[] = "CABC";
    printf("%c", *(str+2));
}

A) C
B) A
C) B
D) Compiler error

✅ Answer: C
Explanation:
Pointer arithmetic → *(str+2) → third character → ‘B’.

---

42.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "ABC";
    char str2[] = "DEF";
    strncat(str1, str2, 2);
    printf("%s", str1);
}

A) ABC
B) ABCDE
C) ABCDEF
D) Compiler error

✅ Answer: B
Explanation:
strncat appends only first 2 characters → “ABCD” → “ABCDE” (careful: ABC + DE = ABCDE).

---

43.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "GATE";
    char str2[10];
    strcpy(str2, str1);
    str2[0] = 'C';
    printf("%s", str2);
}

A) GATE
B) CATE
C) Compiler error
D) CATG

✅ Answer: B
Explanation:
str2 modified → first character replaced → “CATE”.

---

44.

Which function returns pointer to first occurrence of character in a string?

A) strchr()
B) strstr()
C) strcpy()
D) strcat()

✅ Answer: A
Explanation:
strchr(str, ch) → returns pointer to first occurrence of ch.

---

45.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str[10] = "GATE";
    printf("%c", str[strlen(str)-1]);
}

A) G
B) A
C) T
D) E

✅ Answer: D
Explanation:
strlen(str) = 4 → last index = 3 → str[3] = ‘E’.

---

46.

Output:

#include <stdio.h>
int main() {
    char str[] = "GATE";
    printf("%lu", sizeof(str));
}

A) 4
B) 5
C) 6
D) Compiler error

✅ Answer: B
Explanation:
sizeof includes null → 5 bytes.

---

47.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[] = "ABC";
    char str2[] = "abc";
    printf("%d", strcmp(str1, str2));
}

A) 0
B) Negative number
C) Positive number
D) Compiler error

✅ Answer: B
Explanation:
Uppercase ‘A’ < lowercase ‘a’ → strcmp returns negative.

---

48.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "ABC";
    char str2[] = "DEF";
    strcat(str1, str2);
    printf("%s", str1);
}

A) ABC
B) DEF
C) ABCDEF
D) Compiler error

✅ Answer: C
Explanation:
strcat appends str2 → str1 = “ABCDEF”.

---

49.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str[10] = "CABC";
    printf("%d", strlen(str));
}

A) 3
B) 4
C) 5
D) Compiler error

✅ Answer: B
Explanation:
strlen excludes null → “CABC” → 4.

---

50.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[] = "ABC";
    char str2[] = "ABC";
    printf("%d", strcmp(str1, str2));
}

A) 0
B) 1
C) -1
D) Compiler error

✅ Answer: A
Explanation:
Strings equal → strcmp returns 0.

---

51.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str[] = "GATE";
    str[4] = 'X';
    printf("%s", str);
}

A) GATEX
B) GATE
C) Compiler error
D) GAEX

✅ Answer: A
Explanation:
Overwriting null → prints “GATEX” (undefined behavior).

---

52.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "GAT";
    char str2[] = "EG";
    strncat(str1, str2, 1);
    printf("%s", str1);
}

A) GAT
B) GATE
C) GATEG
D) GATE

✅ Answer: B
Explanation:
Appends first character of str2 → GAT + E → GATE.

---

53.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str[] = "CABC";
    printf("%c", str[0]);
}

A) C
B) A
C) B
D) Compiler error

✅ Answer: A
Explanation:
str[0] → first character → ‘C’.

---

54.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "ABC";
    char str2[10] = "XYZ";
    printf("%d", strcmp(str1, str2));
}

A) 0
B) Negative number
C) Positive number
D) Compiler error

✅ Answer: B
Explanation:
ABC < XYZ → strcmp returns negative.

---

55.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str[] = "GATE";
    str[0] = 'C';
    printf("%s", str);
}

A) CATE
B) GATE
C) CATG
D) Compiler error

✅ Answer: A
Explanation:
First character replaced → “CATE”.

---

56.

Which function searches substring in a string?

A) strstr()
B) strchr()
C) strcmp()
D) strcpy()

✅ Answer: A
Explanation:
strstr(haystack, needle) → returns pointer to first occurrence.

---

57.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "GATE";
    char str2[10];
    strcpy(str2, str1);
    printf("%s", str2);
}

A) GATE
B) CATG
C) Compiler error
D) Garbage

✅ Answer: A
Explanation:
str1 copied to str2 → str2 = “GATE”.

---

58.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str[] = "GATE";
    printf("%c", *(str+3));
}

A) G
B) A
C) T
D) E

✅ Answer: D
Explanation:
Pointer arithmetic → *(str+3) → last character → ‘E’.

---

59.

Which of the following replaces first n characters in string?

A) strncpy()
B) strncat()
C) strcpy()
D) strcat()

✅ Answer: A
Explanation:
strncpy(dest, src, n) copies n characters → can overwrite first n.

---

60.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "ABC";
    char str2[] = "DEF";
    strncat(str1, str2, 2);
    printf("%s", str1);
}

A) ABC
B) ABCDE
C) ABCDEF
D) Compiler error

✅ Answer: B
Explanation:
strncat appends first 2 chars → ABC + DE → ABCDE.

---

61.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str[10] = "HELLO";
    printf("%c", str[strlen(str)]);
}

A) H
B) Null character
C) O
D) Compiler error

✅ Answer: B
Explanation:
Index = strlen → null character \0.

---

62.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "ABC";
    char str2[] = "abc";
    printf("%d", strcasecmp(str1, str2));
}

A) 0
B) Negative
C) Positive
D) Compiler error

✅ Answer: A
Explanation:
strcasecmp() ignores case → ABC = abc → 0.

---

63.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "ABC";
    char str2[10] = "XYZ";
    printf("%d", strcmp(str2, str1));
}

A) Positive
B) Negative
C) 0
D) Compiler error

✅ Answer: A
Explanation:
XYZ > ABC → positive return.

---

64.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "HELLO";
    char str2[10];
    strncpy(str2, str1, 3);
    str2[3] = '\0';
    printf("%s", str2);
}

A) HELLO
B) HEL
C) HELL
D) Compiler error

✅ Answer: B
Explanation:
First 3 chars copied → “HEL”.

---

65.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str[] = "GATE";
    printf("%c", str[2]);
}

A) G
B) A
C) T
D) E

✅ Answer: C
Explanation:
str[2] → third character → ‘T’.

---

66.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "CABC";
    char str2[10];
    strcpy(str2, str1);
    str2[0] = 'X';
    printf("%s", str2);
}

A) CABC
B) XABC
C) Compiler error
D) XXBC

✅ Answer: B
Explanation:
First char replaced → XABC.

---

67.

Which function returns pointer to last occurrence of character?

A) strchr()
B) strrchr()
C) strstr()
D) strcpy()

✅ Answer: B
Explanation:
strrchr() → pointer to last occurrence.

---

68.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "HELLO";
    char str2[] = "LO";
    char *p = strstr(str1, str2);
    printf("%s", p);
}

A) HELLO
B) LO
C) LLO
D) Compiler error

✅ Answer: C
Explanation:
strstr returns pointer to first occurrence → “LO” in “HELLO” → “LO” from position → prints “LO”.

---

69.

Output:

#include <stdio.h>
int main() {
    char str[6] = "GATE";
    printf("%lu", sizeof(str));
}

A) 4
B) 5
C) 6
D) Compiler error

✅ Answer: C
Explanation:
Size of array → 6 bytes allocated.

---

70.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str[10] = "HELLO";
    printf("%d", strlen(str));
}

A) 5
B) 6
C) 4
D) Compiler error

✅ Answer: A
Explanation:
strlen counts characters excluding null → 5.

---

71.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "ABC";
    char str2[10] = "DEF";
    strncat(str1, str2, 1);
    printf("%s", str1);
}

A) ABC
B) ABCD
C) ABCDEF
D) Compiler error

✅ Answer: B
Explanation:
strncat → appends first char → ABC + D → ABCD.

---

72.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "ABC";
    char str2[] = "XYZ";
    printf("%d", strcmp(str1, str2));
}

A) 0
B) Negative
C) Positive
D) Compiler error

✅ Answer: B
Explanation:
ABC < XYZ → negative return.

---

73.

Output:

#include <stdio.h>
int main() {
    char str[] = "GATE";
    str[4] = 'X';
    printf("%s", str);
}

A) GATEX
B) GATE
C) Compiler error
D) GAEX

✅ Answer: A
Explanation:
Overwriting null → prints “GATEX”.

---

74.

Which function compares first n characters?

A) strncmp()
B) strncpy()
C) strncat()
D) strcmp()

✅ Answer: A
Explanation:
`strncmp(str1, str2,

75.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "HELLO";
    char str2[] = "HE";
    printf("%d", strncmp(str1, str2, 2));
}

A) 0
B) Positive
C) Negative
D) Compiler error

✅ Answer: A
Explanation:
strncmp() compares first 2 characters → “HE” = “HE” → returns 0.

---

76.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str[] = "GATE";
    printf("%c", str[1]);
}

A) G
B) A
C) T
D) E

✅ Answer: B
Explanation:
str[1] → second character → ‘A’.

---

77.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "CABC";
    char str2[10];
    strcpy(str2, str1);
    str2[2] = 'X';
    printf("%s", str2);
}

A) CAXC
B) CABC
C) Compiler error
D) CXBC

✅ Answer: A
Explanation:
str2 modified → str2[2] = ‘X’ → “CAXC”.

---

78.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str[10] = "HELLO";
    printf("%c", *(str+4));
}

A) H
B) O
C) L
D) Compiler error

✅ Answer: B
Explanation:
Pointer arithmetic → *(str+4) → fifth character → ‘O’.

---

79.

Which function appends n characters from source to destination?

A) strncat()
B) strncpy()
C) strcat()
D) strcpy()

✅ Answer: A
Explanation:
strncat(dest, src, n) → appends first n characters.

---

80.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str[10] = "HELLO";
    printf("%lu", sizeof(str));
}

A) 4
B) 5
C) 10
D) Compiler error

✅ Answer: C
Explanation:
str declared as char[10] → sizeof(str) = 10 bytes.

---

81.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "ABC";
    char str2[10] = "DEF";
    strcat(str1, str2);
    printf("%s", str1);
}

A) ABC
B) DEF
C) ABCDEF
D) Compiler error

✅ Answer: C
Explanation:
strcat appends str2 → str1 = “ABCDEF”.

---

82.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str[] = "GATE";
    printf("%c", str[strlen(str)-2]);
}

A) G
B) A
C) T
D) E

✅ Answer: C
Explanation:
strlen = 4 → index -2 → str[2] = ‘T’.

---

83.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[] = "HELLO";
    char str2[10];
    strncpy(str2, str1, 4);
    str2[4] = '\0';
    printf("%s", str2);
}

A) HELLO
B) HELL
C) HEL
D) Compiler error

✅ Answer: B
Explanation:
Copies first 4 chars → “HELL”.

---

84.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str[] = "CABC";
    str[3] = '\0';
    printf("%s", str);
}

A) CABC
B) CAB
C) Compiler error
D) CA

✅ Answer: B
Explanation:
str[3] = ‘\0’ → string truncated → “CAB”.

---

85.

Which function finds last occurrence of a character?

A) strchr()
B) strrchr()
C) strstr()
D) strcpy()

✅ Answer: B
Explanation:
strrchr() → pointer to last occurrence.

---

86.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str[10] = "HELLO";
    printf("%s", strchr(str, 'L'));
}

A) LLO
B) HELLO
C) LL
D) Compiler error

✅ Answer: A
Explanation:
strchr() returns pointer to first occurrence → prints “LLO”.

---

87.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "GATE";
    char str2[] = "AT";
    char *p = strstr(str1, str2);
    printf("%s", p);
}

A) GATE
B) AT
C) ATE
D) Compiler error

✅ Answer: C
Explanation:
strstr() returns pointer to substring → “ATE”.

---

88.

Output:

#include <stdio.h>
int main() {
    char str[6] = "GATE";
    printf("%lu", sizeof(str));
}

A) 4
B) 5
C) 6
D) Compiler error

✅ Answer: C
Explanation:
Array size = 6 → sizeof(str) = 6.

---

89.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "ABC";
    char str2[] = "ABC";
    printf("%d", strcmp(str1, str2));
}

A) 0
B) Negative
C) Positive
D) Compiler error

✅ Answer: A
Explanation:
Strings equal → 0.

---

90.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str[] = "GATE";
    printf("%c", str[0]);
}

A) G
B) A
C) T
D) E

✅ Answer: A
Explanation:
First character → ‘G’.

---

91.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "HELLO";
    char str2[10];
    strcpy(str2, str1);
    str2[1] = 'A';
    printf("%s", str2);
}

A) HELLO
B) HALLO
C) HLLLO
D) Compiler error

✅ Answer: B
Explanation:
str2 modified → second character replaced → “HALLO”.

---

92.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "ABC";
    char str2[] = "XYZ";
    printf("%d", strcmp(str2, str1));
}

A) Positive
B) Negative
C) 0
D) Compiler error

✅ Answer: A
Explanation:
XYZ > ABC → positive return.

---

93.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "HELLO";
    char str2[10];
    strncpy(str2, str1, 3);
    str2[3] = '\0';
    printf("%s", str2);
}

A) HELLO
B) HEL
C) HELL
D) Compiler error

✅ Answer: B
Explanation:
Copies first 3 characters → “HEL”.

---

94.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str[] = "GATE";
    printf("%c", str[strlen(str)-1]);
}

A) G
B) A
C) T
D) E

✅ Answer: D
Explanation:
Last character → ‘E’.

---

95.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "HELLO";
    char str2[] = "HE";
    printf("%d", strncmp(str1, str2, 2));
}

A) 0
B) Negative
C) Positive
D) Compiler error

✅ Answer: A
Explanation:
First 2 characters equal → returns 0.

---

96.

Which function concatenates two strings safely with n characters?

A) strcat()
B) strncat()
C) strncpy()
D) strcpy()

✅ Answer: B
Explanation:
strncat() appends at most n characters → safer than strcat.

---

97.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "HELLO";
    char str2[10] = "LO";
    printf("%s", strstr(str1, str2));
}

A) LO
B) HELLO
C) LLO
D) Compiler error

✅ Answer: C
Explanation:
strstr → pointer to first occurrence → “LO” → prints “LO” from position → “LO”.

---

98.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str[] = "CABC";
    str[1] = '\0';
    printf("%s", str);
}

A) CABC
B) C
C) AB
D) Compiler error

✅ Answer: B
Explanation:
str[1] = ‘\0’ → string truncated → “C”.

---

99.

Output:

#include <stdio.h>
int main() {
    char str[6] = "GATE";
    printf("%lu", sizeof(str));
}

A) 4
B) 5
C) 6
D) Compiler error

✅ Answer: C
Explanation:
Array of size 6 → sizeof(str) = 6.

---

100.

Output:

#include <stdio.h>
#include <string.h>
int main() {
    char str1[10] = "HELLO";
    char str2[] = "EL";
    char *p = strstr(str1, str2);
    printf("%s", p);
}

A) ELLO
B) HELLO
C) LO
D) Compiler error

✅ Answer: A
Explanation:
strstr → pointer to first occurrence → prints substring starting from “EL” → “ELLO”.

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