我试图将一个结构保存到一个文件中,然后在另一个程序中再次读取它.我以前从来没有遇到过这样的问题,但至少据我所知,我从来没有尝试过写一个双变量的值。56.806201550387598
到一个文件中。并不是说我不知道为什么这个数字会产生什么问题,但是每当我试图将一个包含这个值的结构写入文件时,这个字段和在它之后声明的任何字段,都只能从结构声明中读出初始化值。
#include <fstream>
#include <iostream>
#include <string>
using namespace std;
typedef struct statsSet{
int pathCount = 0;
double vMinMean = 0;
int imgsFound = 0;
int minWidth = INT_MAX;
int maxWidth = 0;
}statsSet;
void wrightToFile(statsSet sSet){
FILE* of = fopen ("imgStats2.dat", "w");
fwrite (&sSet, sizeof(statsSet), 1, of);
fclose (of);
}
statsSet readFromFile(){
statsSet statReadIn;
FILE *ifl = fopen ("imgStats2.dat" , "r");
fread(&statReadIn, sizeof(statsSet), 1, ifl);
fclose (ifl);
return statReadIn;
}
void pr(statsSet statReadIn){
cout << "pathCount: " << statReadIn.pathCount << "\n";
cout << "vMinMean: " << statReadIn.vMinMean<< "\n";
cout << "imgsFound: " << statReadIn.imgsFound<< "\n";
cout << "minWidth: " << statReadIn.minWidth<< "\n";
cout << "maxWidth: " << statReadIn.maxWidth<< "\n";
cout << "--------\n";
}
int main( int argc, char** argv ){
statsSet statTest;
statsSet statReadIn;
statTest.pathCount = 129;
statTest.imgsFound = 129;
statTest.minWidth = 488;
statTest.maxWidth = 501;
statTest.vMinMean = 56.806201550387591; // OK
wrightToFile(statTest);
statReadIn = readFromFile();
pr(statReadIn);
statTest.vMinMean = 56.806201550387598; //breaks
wrightToFile(statTest);
statReadIn = readFromFile();
pr(statReadIn);
statTest.vMinMean = 56.806201550387605; // OK
wrightToFile(statTest);
statReadIn = readFromFile();
pr(statReadIn);
}
输出。
pathCount: 129
vMinMean: 56.8062
imgsFound: 129
minWidth: 488
maxWidth: 501
--------
pathCount: 129
vMinMean: 0
imgsFound: 0
minWidth: 2147483647
maxWidth: 0
--------
pathCount: 129
vMinMean: 56.8062
imgsFound: 129
minWidth: 488
maxWidth: 501
--------
我到底做错了什么?
我使用的是Windows 10、Visual Studio Code和MinGW-w64。
使用写二进制模式。文本模式对于二进制数据会很随机。
FILE* of = fopen ("imgStats2.dat", "wb");
和
FILE *ifl = fopen ("imgStats2.dat" , "rb");