strcat() in C - Source Code Example

In this source code example, we will see how to use the strcat() function in C programming with an example.

strcat() Function Overview

The strcat() function in C is a standard library function that concatenates two strings and returns the concatenated string. The destination string should be large enough to store the concatenated result. 

Key Points: 

- Located in the <string.h> header file. 

- It appends the source string at the end of the destination string. 

- The destination string must be large enough to hold the result. Otherwise, undefined behavior occurs.

Source Code Example

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

int main() {
    char dest[50] = "Hello, ";
    char src[] = "world!";

    // Using strcat to concatenate src onto dest
    strcat(dest, src);
    printf("%s\n", dest);

    // Adding more to the string
    strcat(dest, " Have a good day.");
    printf("%s\n", dest);

    return 0;
}

Output

Hello, world!
Hello, world! Have a good day.

Explanation

1. We start with a dest string containing "Hello, " and a src string with "world!".

2. With strcat(), we append the src string to the dest string, making it "Hello, world!".

3. We add another string, " Have a good day.", to the dest string using strcat(), showcasing its ability to continuously concatenate strings.