格式化io与非格式化io得对比理解

测试函数1

#include<stdio.h>
#include<string.h>
int main()
{
    int a[5]={
  65,66,67,68};
    char value[10],i;
    FILE *pf;

    if(!(pf = fopen("printf.txt","w+")))
    {
        perror("open file:");
        return -1;
    }

    fprintf(pf,"%d