Ostep wgrep

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
int main(int argc, char *argv[]){

    int i; 
    FILE *rfp ; 
    char buffer[512];
  
    if(argc < 2){
        printf("wgrep: searchterm [file ...]\n");
        exit(1);
    }
    else if (argc == 2){
		while(fgets(buffer,sizeof(buffer),stdin)){
			if(strstr(buffer,argv[1]))
				printf("%s",buffer);
		}
    }
    else{
        for(i = 2 ; i < argc ; i++){
            rfp = fopen(argv[i] , "r");
            if(rfp == NULL){
                printf("wgrep: cannot open file\n");
                exit(1);
            }
            while(fgets(buffer , sizeof(buffer) , rfp)){
                if(strstr(buffer , argv[1])){
                    printf("%s" , buffer);
                }
            }
            fclose(rfp);
        }


    }

    return 0;
}