String comparison - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of strcmp with equal strings

What is the output of the following C code?

C

#include <stdio.h>
#include <string.h>

int main() {
    char a[] = "hello";
    char b[] = "hello";
    int result = strcmp(a, b);
    printf("%d", result);
    return 0;
}

A Undefined behavior

B 0

C -1

D 1

💡 Hint

strcmp returns 0 when strings are equal.

The strcmp function returns 0 when both strings are exactly the same.

❓ Predict Output

intermediate

Output of strcmp with first string less than second

What is the output of this C code snippet?

C

#include <stdio.h>
#include <string.h>

int main() {
    char a[] = "apple";
    char b[] = "banana";
    int result = strcmp(a, b);
    printf("%d", result);
    return 0;
}

A A negative number

B 0

C A positive number

D Compilation error

💡 Hint

strcmp returns negative if first string is less in lexicographic order.

Since "apple" is lexicographically less than "banana", strcmp returns a negative value.

❓ Predict Output

advanced

Output of strcmp with case difference

What will this C program print?

C

#include <stdio.h>
#include <string.h>

int main() {
    char a[] = "Hello";
    char b[] = "hello";
    int result = strcmp(a, b);
    printf("%d", result);
    return 0;
}

A A positive number

B 0

C Runtime error

D A negative number

💡 Hint

Uppercase letters have lower ASCII codes than lowercase letters.

Since 'H' (ASCII 72) is less than 'h' (ASCII 104), strcmp returns a negative number.

❓ Predict Output

advanced

Output of strcmp with empty string

What is the output of this C code?

C

#include <stdio.h>
#include <string.h>

int main() {
    char a[] = "";
    char b[] = "nonempty";
    int result = strcmp(a, b);
    printf("%d", result);
    return 0;
}

A A negative number

B 0

C A positive number

D Segmentation fault

💡 Hint

Empty string is less than any non-empty string.

strcmp returns a negative number because empty string is lexicographically less than "nonempty".

❓ Predict Output

expert

Value of variable after strcmp with partial match

What is the value of variable result after running this code?

C

#include <stdio.h>
#include <string.h>

int main() {
    char a[] = "test123";
    char b[] = "test124";
    int result = strcmp(a, b);
    printf("%d", result);
    return 0;
}

A 0

B 1

C -1

D Undefined behavior

💡 Hint

strcmp compares character by character until difference found.

The strings differ at the last character: '3' (ASCII 51) vs '4' (ASCII 52), so strcmp returns a negative number (-1).