file io in c is done through code example

Example 1: read files in c

#include<stdio.h>
int main(){
	FILE *in=fopen("name_of_file.txt","r");
	char c;
	while((c=fgetc(in))!=EOF)
		putchar(c);
	fclose(in);
	return 0;
}

Example 2: c file

#include <stdio.h>
#include <stdlib.h>

int main() {
   	printf("Hello Word!");
    return 0;
}