String input and output in C - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to print the string stored in name.

C

#include <stdio.h>

int main() {
    char name[20] = "Alice";
    printf([1], name);
    return 0;
}

Drag options to blanks, or click blank then click option'

A"%s\n"

B"%d\n"

C"%c\n"

D"%f\n"

Attempts:

3 left

💡 Hint

Common Mistakes

Using %d or %c instead of %s for strings.

Forgetting to add quotes around the format specifier.

Use "%s" in printf to print a string variable.

2fill in blank

medium

Complete the code to read a string input from the user into the array input.

C

#include <stdio.h>

int main() {
    char input[50];
    printf("Enter your name: ");
    scanf([1], input);
    printf("Hello, %s!\n", input);
    return 0;
}

Drag options to blanks, or click blank then click option'

A"%d"

B"%s"

C"%c"

D"%f"

Attempts:

3 left

💡 Hint

Common Mistakes

Using %d or %c instead of %s in scanf.

Adding & before the array name when reading strings.

Use "%s" in scanf to read a string input.

3fill in blank

hard

Fix the error in the code to correctly read a string with spaces from the user.

C

#include <stdio.h>

int main() {
    char fullName[100];
    printf("Enter your full name: ");
    fgets([1], 100, stdin);
    printf("Hello, %s", fullName);
    return 0;
}

Drag options to blanks, or click blank then click option'

AfullName[100]

B&fullName

CfullName

D*fullName

Attempts:

3 left

💡 Hint

Common Mistakes

Using & before the array name with fgets.

Using array indexing like fullName[100] which is out of bounds.

fgets requires the array name without & to read the string including spaces.

4fill in blank

hard

Fill both blanks to create a string copy using strcpy.

C

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

int main() {
    char source[] = "Hello";
    char destination[20];
    [1](destination, [2]);
    printf("Copied string: %s\n", destination);
    return 0;
}

Drag options to blanks, or click blank then click option'

Astrcpy

Bstrncpy

Csource

Ddestination

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping source and destination arguments.

Using strncpy without specifying length.

Use strcpy(destination, source) to copy the string from source to destination.

5fill in blank

hard

Fill all three blanks to concatenate two strings safely using strncat.

C

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

int main() {
    char str1[20] = "Hello, ";
    char str2[] = "World!";
    [1](str1, [2], [3]);
    printf("Concatenated string: %s\n", str1);
    return 0;
}

Drag options to blanks, or click blank then click option'

Astrncat

Bstr2

C6

Dstrlen(str2)

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect length value for strncat.

Swapping the order of arguments.

Use strncat(str1, str2, strlen(str2)) to concatenate str2 to str1 safely.