C++txt文件读写

一、读取txt中的矩阵

txt中存储3*3的矩阵，以逗号隔开：

int a[3][3];

ifstream fin(_fileName, ios::in);

char buffer[256];

int idx=0;

if (fin.is_open())

{

while (!fin.eof())

{

fin.getline(buffer, 100);

char *substr = strtok(buffer, ",");

vector<string> charlist;

while (substr != NULL)

{

string str(substr);

charlist.push_back(str);

substr = strtok(NULL, ",");

}

if (charlist.size() != 3) continue;

 a[idx][0]=atoi(charlist[0].c_str()) ;//float类型可以用atof

 a[idx][0]=atoi(charlist[1].c_str()) ;

 a[idx][0]=atoi(charlist[2].c_str()) ;

 }

}

二、写文件

将文件保存到txt中：

ofstream os("data.txt", ios::app);

os << "1"<<","<<"2"<<endl;//endl为换行符

os.close();