本文主要是利用C函式fread、fwrite、fscanf以及C++檔案流ifstream、ofstream等函式從檔案讀寫。

#include <stdio.h>
#include <stdlib.h>
#include <iostream>
#include <fstream>
#include <sstream>
#include <String>
using namespace std;
struct student
{
	int num;
	int age;
	char name[30];
	//使用char *name;讀取結構體出錯
};
//寫入結構體陣列
void writeStruct()
{
    student* listStruct;
	const int Size = 5;
	listStruct = (struct student*)malloc(sizeof(struct student) * Size);
	FILE *fp;
	for (int i = 0; i < Size; i++){
		listStruct[i].num = i;
		listStruct[i].age = i * 10;
		strcpy(listStruct[i].name, "name");
	}
	fp = fopen("test.txt", "wb");
	if (fp == NULL){
		printf("Open File failed.\n");
		exit(0);
	}
	for (int i = 0; i < Size; i++){
		if (fwrite(&listStruct[i], sizeof(struct student), 1, fp) != 1){
			printf("File Write Error.\n");
		}
	}
	printf("write data success.\n");
	fclose(fp);
}

//讀取到結構體
void readStruct(){
	FILE * fp;
	if ((fp = fopen("test.txt", "rb")) == NULL){
		printf("Open File failed.\n");
		exit(0);
	}
	student one;
	printf("read data:\n");
	while (fread(&one, sizeof(struct student), 1, fp) == 1){
		printf("%d %d %s\n", one.num, one.age, one.name);
	}
	fclose(fp);
}


//按照指定格式從文字中讀取多行資料
void readFile(){
	FILE *fp;
	fp = fopen("read.txt", "r");
	if (fp == NULL){
		printf("Open File failed.\n");
		exit(0);
	}
	int a;
	float c;
	char str[100];
	while (!feof(fp)){
		fscanf(fp, "%d%s%f", &a, &str, &c);
		printf("Line:%d %s %.1f\n", a, str, c);
	}
	fclose(fp);
}

//C++ 檔案流讀寫
void writeStream(){
	ofstream out;
	out.open("11.txt", ios::trunc);
	if (!out.is_open()){
		cout << "open File Failed." << endl;
		return;
	}
	char a = 'a';
	for (int i = 0; i < 5; i++){
		out << i << "\t" << a << endl;
		a++;
	}
	out.close();
}

void readStream(){
	ifstream in;
	in.open("11.txt", ios::in);
	if (!in.is_open()){
		cout << "open File Failed." << endl;
		return;
	}
	string strOne;
	while (getline(in, strOne)){
		stringstream ss;
		ss << strOne;
		int a;
		char c;
		ss >> a >> c;
		cout << a <<"  "<< c << endl;
	}

}


int main(){
	writeStruct();
	readStruct();
	//readFile();
	//writeStream();
	//readStream();
	return 0;
}
 

2、按照指定格式從文字讀取資料

3、C++檔案流讀寫