C/C++从文本文件读取数据

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本文主要是利用C函数fread、fwrite、fscanf以及C++文件流ifstream、ofstream等函数从文件读写。

#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;读取结构体出错};//写入结构体数组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);}//读取到结构体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);}//按照指定格式从文本中读取多行数据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++ 文件流读写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;}

1、测试读写结构体数组

2、按照指定格式从文本读取数据

3、C++文件流读写

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