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

int main(void)
{
    int i = 0;
    FILE *fp = NULL;
    char *filename = "c:/2.txt";
    char a[30] = "adfhgiohgoihg";
    fp = fopen(filename, "r+");
    if(fp == NULL)
    {
        printf("func fopen()err\n");
        return ;
    }
   
    printf("打开文件成功\n");
   
    for(i=0; i<strlen(a); i++)
    {
        fputc(a[i],fp);
    }
   
    fclose(fp);
    system("pause");
    return 0;
}

//错误提示信息
//[Error] return-statement with no value, in function returning 'int' [-fpermissive]

int main(void)
{
    ……
    if(fp == NULL)
    {
        printf("func fopen()err\n");
        return ;
    }