C/C++的文件IO函数你知道吗

std::FILE* fopen( const char* filename, const char* mode );

int fclose(FILE *stream)

int fprintf(FILE *stream, const char *format, ... );
fprintf()函数根据指定的format(格式)发送信息(参数)到由stream(流)指定的文件.
int fscanf(FILE *stream, const char *format, ...)
C库函数 int fscanf(FILE *stream, const char *format, ...) 从流stream读取格式化输入。

//在这几条语句中，filel都被截断
ofstream out ("filel"); //隐含以输出模式打开文件并截断文件
ofstream out2("file1", ofstream::out); //隐含地截断文件
ofstream out3("file1", ofstream::out | ofstream::trunc);
//为了保留文件内容，显式指定app模式
ofstream app("file2"， ofstream::app); //隐含为输出模式
ofstream app2("fi1e2", ofstream::out | ofstream::app);

#include<iostream>
#include<string>
#include<algorithm>
#include<sstream>
#include<fstream>
#include<stdio.h>
using namespace std;
const int MAX_NUM = 100;
int a[MAX_NUM];
int n = 2;
int main(int argc, char* argv[])
{
    FILE* file4 = fopen("d.txt", "w");
    if (!file4) {
        printf("file4 open error!\n");
        return -1;
    }
    //fprintf(file4, "name age sex position\n");
    int age, sex;
    char name[50], position[50];
    printf("please input 2 date : name age sex position:\n");
    while (n--)
    {
        scanf("%s %d %d %s", &name, &age, &sex, &position);
        fprintf(file4, "%s %d %d %s\n", name, age, sex, position);
    }
    fclose(file4);
    FILE* file5 = fopen("d.txt", "r");
    if (!file5) {
        printf("file5 open error!");
        return -1;
    }
    int m = 2, ans, ans1;
    while (m--)
    {
        fscanf(file5, "%s %d %d %s", &name, &age, &sex, &position);
        printf("%s %d %d %s\n", name, age, sex, position);
    }
    fclose(file5);
    fstream file1("d.txt");
    if (!file1) {
        cout << "file1 open error! " << endl;
        return -1;
    }
    string tmp;
    vector<string>str;
    while (file1 >> tmp)
    {
        str.push_back(tmp);
        cout << tmp << endl;
    }
    ifstream file2("b.txt", ios::in);
    if (!file2) {
        cout << "file2 open error! " << endl;
        return -1;
    }
    ofstream file3("c.txt", ios::out);
    if (!file3) {
        cout << "file3 open error! " << endl;
        return -1;
    }
    while (n--)
    {
        file3 << n<<' ';
    }
    file1.close();
    file2.close();
    file3.close();
    return 0;
}