C++读写文本数据
1、C++读写二进制文件
/*****************************************************************
* \author DreamerZhang
* \date 2019.08.27
* \brief 读取二进制文件，数据类型为short
* \param
fileName-文件名
readData-读取的数据
dataLength-返回的数据长度
* \return true-成功 false - 失败
*
*****************************************************************/
bool readFromFile(std::string fileName, short* readData, int* dataLength);
/*****************************************************************
* \author DreamerZhang
* \date 2019.08.27
* \brief 保存二进制文件，数据类型为short
* \param
fileName-文件名
data-写入的数据
dataLength-写入的数据长度
* \return true-成功 false - 失败
*
*****************************************************************/
bool writeToFile(std::string fileName, short* data, int dataLength);
bool FileTest::readFromFile(std::string fileName, short* readData, int* dataLength)
{
//seekg()是对输入流的操作 g是get缩写; seekp()是对输出流的操作 p是put缩写
//它有三个取值: ios::beg：表示输入流的开始位置
// ios::cur：表示输入流的当前位置
// ios::end：表示输入流的结束位置
if (fileName.empty()) {
return false;
}
ifstream inFile;
//打开文件
inFile.open(fileName, ios::binary);
if (!inFile.is_open()) {
std::cout << "Open File Failed.\n" << endl;
return false;
}
//获取文件长度
inFile.seekg(0, ios::end);
int bytes = inFile.tellg();
int length = bytes / sizeof(short);
inFile.seekg(0, ios::beg);
//读取文件
inFile.read((char*)readData, sizeof(short) * length);//注意指针转为char*
inFile.close();
*dataLength = length;
return true;
}
bool FileTest::writeToFile(std::string fileName, short* data, int dataLength)
{
if (fileName.empty()) {
return false;
}
ofstream outFile;
//打开文件
outFile.open(fileName, ios::binary);
if (!outFile.is_open()) {
std::cout << "Open File Failed.\n" << endl;
return false;
}
//写入数据
outFile.write((char*)data, dataLength * sizeof(short));
outFile.close();
return true;
}
2、C++读写ASCII文件（cin & cout）
/*****************************************************************
* \author DreamerZhang
* \date 2019.10.22
* \brief 读取txt文件(ascii码)，数据类型为short
* \param
fileName-文件名
readData-读取的数据
dataLength-返回的数据长度
* \return true-成功 false - 失败
*
*****************************************************************/
bool readFromFile_Ascii(std::string fileName, short* readData, int* dataLength);
/*****************************************************************
* \author DreamerZhang
* \date 2019.10.22
* \brief 保存txt文件(ascii码)，数据类型为short
* \param
fileName-文件名
data-写入的数据
dataLength-写入的数据长度
* \return true-成功 false - 失败
*
*****************************************************************/
bool writeToFile_Ascii(std::string fileName, short* data, int dataLength);
bool FileTest::readFromFile_Ascii(std::string fileName, short* readData, int* dataLength)
{
if (fileName.empty()) {
return false;
}
ifstream inFile;
//打开文件
inFile.open(fileName, ios::in);
if (!inFile.is_open()) {
std::cout << "Open File Failed.\n" << endl;
return false;
}
//获取文件长度
inFile.seekg(0, ios::end);
int bytes = inFile.tellg();
int length = bytes / sizeof(short);
inFile.seekg(0, ios::beg);
*dataLength = length;
//读入文件
for (int i = 0; i < length; i++) {
inFile >> readData[i];
}
inFile.close();
return true;
}
bool FileTest::writeToFile_Ascii(std::string fileName, short* data, int dataLength)
{
if (fileName.empty()) {
return false;
}
ofstream outFile;
outFile.open(fileName, ios::out);
if (!outFile.is_open()) {
std::cout << "Open File Failed.\n" << endl;
return false;
}
for (int i = 0; i < dataLength; i++)
{
outFile << data[i]<
3、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（以前测试写着玩儿的）。
#include
#include
#include
#include
#include
#include
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
