Concatenate two strings with C.

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

int main()
{
    char str1[100], str2[100];

    /* Input two strings from user */
    printf("Enter first string: ");
    gets(str1);
    printf("Enter second string: ");
    gets(str2);

    /* Concatenate str1 with str2 */
    strcat(str1, str2);
    printf("Concatenated string = %s", str1);

    return 0;
}

Output

Enter first string: Rezaul
Enter second string: Karim
Concatenated string = RezaulKarim