C program for concatenate two strings

C program for concatenate two strings or append string with another string.



1) Using library strcat() function

  #include<stdio.h>  
 #include<string.h>  
 int main()  
 {  
   char str1[100], str2[100];  
   printf("Enter String-1 :");  
   gets(str1);  
   printf("Enter String-2 :");  
   gets(str2);  
   /* Standard library function of header file string.h */  
   strcat(str1,str2);  
   printf("\nAfter Concatenate Operation str1 = %s",str1);  
   return 0;  
 }  

2) Without using library function strcat()

 #include<stdio.h>  
 int main()  
 {  
   char str1[100],str2[100];  
   int i=0,j=0;  
   printf("Enter String-1 : ");  
   gets(str1);  
   printf("Enter String-2 : ");  
   gets(str2);  
   while( str1[i] != '\0' )  
     i++;  
   while( str2[j] != '\0' )  
   {  
     str1[i] = str2[j];  
     j++;  
     i++;  
   }  
   str1[i] = '\0';  
   printf("\n\nAfter Concatenate Operation str1 = %s",str1);  
   return 0;  
 }