文件读写最简单问题，编译器是Eclipse C++，fopen函数总是返回空指针，怎么回事？

#include <stdio.h>
#include <fstream>
using namespace std;

int main(){
    FILE *fp;
    fp=fopen("1.txt","r+");
    if(fp==NULL){
        printf("there is no character.");
    }
    char buff[255];
    fscanf(fp,"%s",buff);
    printf("%s",buff);
}

文件目录如下