In C, the **`strcat()` function** is used to concatenate two strings.

# Prototype declaration

The `strcat()` function is declared as follows:

```C
strcat(char *dest, const char *src)
```

# How it works

The function takes two strings as input; the _destination string_, and the _source string_. The pointer of the source string is appended to the end of the destination string, thus concatenating both strings.

Look at the following illustrations to get a better idea of how the `strcat()` function works:

## Example

The following pieces of code will concatenate two strings using the `strcat()` function:

#include <stdio.h>
#include <string.h>
int main()
{
    char destination[] = "Hello ";
    char source[] = "World!";
    strcat(destination,source);
    printf("Concatenated String: %s\n", destination);
    return 0;
}


In addition to modifying the original destination string, the `strcat()` function also returns a pointer to that string. 

Therefore, we can directly pass the `strcat()` function to the `printf()` function. 


#include <stdio.h>
#include <string.h>
int main()
{
    char destination[] = "Hello ";
    char source[] = "World!";
    printf("Concatenated String: %s\n",  strcat(destination,source));
    return 0;
}


Concatenating two strings in C

Prototype declaration

How it works

Example