write a function that concatenate two strings in c without using strcat code example

Example 1: c concatenate strings

char str[80];
strcpy(str, "these ");
strcat(str, "strings ");
strcat(str, "are ");
strcat(str, "concatenated.");

Example 2: concatenate two strings in c

#include <stdio.h>
#include <string.h>
int main()
{
  char a[1000], b[1000];

  printf("Enter the first string\n");
  gets(a);

  printf("Enter the second string\n");
  gets(b);

  strcat(a, b);

  printf("String obtained on concatenation: %s\n", a);

  return 0;
}