我正在尝试读取我创建的.bin文件,其中包含两个整数和一个字符串。 int显示正常,但不知何故,字符串输出显示奇怪的符号。
这是写脚本:
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
struct student{
int no;
string name;
int score;
};
int main(){
fstream myFile;
myFile.open("data.bin", ios::trunc | ios::out | ios::in | ios::binary);
student jay, brad;
jay.no = 100;
jay.name = "Jay";
jay.score = 95;
brad.no = 200;
brad.name = "Brad";
brad.score = 83;
myFile.write(reinterpret_cast<char*>(&jay),sizeof(student));
myFile.write(reinterpret_cast<char*>(&brad),sizeof(student));
myFile.close();
cin.get();
return 0;
}
这是阅读脚本:
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
struct student{
int no;
string name;
int score;
};
int main(){
fstream myFile;
myFile.open("data.bin", ios::in | ios::binary);
student readFile;
myFile.seekp(1*sizeOf(student)); //I use this because I want only specific position
//to be shown, for example I put 1 to show only Brad
myFile.read(reinterpret_cast<char*>(&readFile),sizeof(student));
cout << "No : " << readFile.no << endl;
cout << "Name : " << readFile.name << endl;
cout << "Score: " << readFile.score << endl;
myFile.close();
cin.get();
return 0;
}
结果将是这样的:
No : 200
Name : ñ∩K
Score: 83
字符串显示“ñ∩K”而不是“Brad”。我尽量不使用seekp
,并且使用了两次读取:
myFile.read(reinterpret_cast<char*>(&readFile),sizeof(student));
cout << "No : " << readFile.no << endl;
cout << "Name : " << readFile.name << endl;
cout << "Score: " << readFile.score << endl;
myFile.read(reinterpret_cast<char*>(&readFile),sizeof(student));
cout << "No : " << readFile.no << endl;
cout << "Name : " << readFile.name << endl;
cout << "Score: " << readFile.score << endl;
结果将是:
No : 100
Name : Jay
Score: 95
No : 200
Name : ε@
Score: 83
正如你所看到的,第一个位置显示“杰伊”很好,但下一个位置不是。知道出了什么问题吗?我是C ++的新手。
你写的文件不是字符串,而是std::string
对象的内部结构。可能那是指针。当你重读它时,指针将指向无效的东西。你很幸运能得到任何输出而不是崩溃,或者从你的鼻孔飞来的恶魔。