String comparison - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to compare two strings using the correct function.

C

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

int main() {
    char str1[] = "apple";
    char str2[] = "apple";
    if ([1](str1, str2) == 0) {
        printf("Strings are equal.\n");
    } else {
        printf("Strings are not equal.\n");
    }
    return 0;
}

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Astrcmp

Bstrcpy

Cstrlen

Dstrcat

Attempts:

3 left

💡 Hint

Common Mistakes

Using strcpy instead of strcmp.

Using strlen which returns length, not comparison.

The strcmp function compares two strings and returns 0 if they are equal.

2fill in blank

medium

Complete the code to check if two strings are different.

C

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

int main() {
    char a[] = "cat";
    char b[] = "dog";
    if ([1](a, b) != 0) {
        printf("Strings are different.\n");
    } else {
        printf("Strings are the same.\n");
    }
    return 0;
}

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Astrcmp

Bstrcpy

Cstrlen

Dstrchr

Attempts:

3 left

💡 Hint

Common Mistakes

Using strcpy which copies strings.

Using strlen which returns length.

strcmp returns a non-zero value when strings differ.

3fill in blank

hard

Fix the error in the code to correctly compare strings ignoring case.

C

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

int main() {
    char s1[] = "Hello";
    char s2[] = "hello";
    if ([1](s1, s2) == 0) {
        printf("Strings are equal ignoring case.\n");
    } else {
        printf("Strings are different.\n");
    }
    return 0;
}

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Astrcmp

Bstrncmp

Cstrcasecmp

Dstrcpy

Attempts:

3 left

💡 Hint

Common Mistakes

Using strcmp which is case sensitive.

Using strcpy which copies strings.

strcasecmp compares strings ignoring case differences.

4fill in blank

hard

Fill both blanks to create a dictionary-like structure that maps words to their lengths if length is greater than 3.

C

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

int main() {
    char *words[] = {"apple", "cat", "banana", "dog"};
    int lengths[4];
    for (int i = 0; i < 4; i++) {
        if ([1](words[i]) [2] 3) {
            lengths[i] = strlen(words[i]);
            printf("%s: %d\n", words[i], lengths[i]);
        }
    }
    return 0;
}

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Astrlen

B>

C<

Dstrcmp

Attempts:

3 left

💡 Hint

Common Mistakes

Using strcmp instead of strlen for length.

Using less than operator instead of greater than.

Use strlen to get the length of the word and check if it is greater than 3.

5fill in blank

hard

Fill all three blanks to create a filtered dictionary of words with length greater than 4, mapping uppercase words to their lengths.

C

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

void to_upper(char *dest, const char *src) {
    int i = 0;
    while (src[i]) {
        dest[i] = [1](src[i]);
        i++;
    }
    dest[i] = '\0';
}

int main() {
    char *words[] = {"apple", "cat", "banana", "dog"};
    char upper[20];
    int lengths[4];
    for (int i = 0; i < 4; i++) {
        if (strlen(words[i]) [2] 4) {
            to_upper(upper, words[i]);
            lengths[i] = strlen(words[i]);
            printf("%s: %d\n", [3], lengths[i]);
        }
    }
    return 0;
}

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Atoupper

B>

Cupper

Dtolower

Attempts:

3 left

💡 Hint

Common Mistakes

Using tolower instead of toupper.

Printing the original word instead of the uppercase version.

Use toupper to convert characters to uppercase, check if length is greater than 4, and print the uppercase word.