strncat(): Concatenation of part of string

#include <stdio.h>
#include <string.h>
int main(void){
char var1[20]="plus2net";
char var2[]="welcome to ";
strncat(var2,var1,5);
printf(var2);
return 0;
}

welcome to plus2

strncat(destination_string, source_string,n);

• Source string is not affected
• Part of the Source string is added at the end of the destination string.

Example: Custom Implementation of strncat()

#include <stdio.h>
#include <string.h>
char* custom_strncat(char* dest, const char* src, size_t n) {
    char* ptr = dest + strlen(dest);  // Move pointer to the end of dest
    while (*src && n--) {
        *ptr++ = *src++;  // Append characters
    }
    *ptr = '\0';  // Null-terminate dest
    return dest;
}

int main() {
    char dest[20] = "Hello, ";
    char src[] = "World!";
    custom_strncat(dest, src, 3);  // Concatenate first 3 characters of src
    printf("Result: %s\n", dest);  // Output: Hello, Wor
    return 0;
}

Result: Hello, Wor

Example: Ensuring Enough Space in Destination String

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

int main() {
    char dest[20] = "Plus2Net";
    char src[] = "C Tutorial";

    // Ensure enough space in dest before concatenating
    if (sizeof(dest) - strlen(dest) - 1 >= strlen(src)) {
        strncat(dest, src, 5);  // Concatenate first 5 characters
        printf("Concatenated string: %s\n", dest);  // Output: Plus2NetC Tut
    } else {
        printf("Not enough space in destination string!\n");
    }
    return 0;
}

Concatenated string: Plus2NetC Tut