c++ - 用 C++ 读取文本文件

Question

我正在 Ubuntu 上的 OpenCV 上工作。我正在尝试读取包含数字的文本文件，但我不断收到垃圾值，并且每次函数循环时都会重复相同的值。这是该部分代码:

FILE* fid = fopen("/trial","r");
while (fgetc(fid) != EOF)
{
    fscanf(fid, "%f", &trainsample);
    cout << trainsample << endl;
    cvSetReal2D(traindata, i, j, trainsample);
    j = j + 1;
    if (j == 6)
        i = i + 1;
}

Answer 1

为什么不使用 C++ ifstream 来完成此任务？

#include <iostream>
#include <fstream>

int main(){
    std::ifstream fileStream("/trail");
    double trainsample;
    if(!fileStream.good()){
        std::cerr << "Could not open file." << std::endl;
        return 1;
    }
    while(fileStream >> trainsample){           
        std::cout << trainsample << std::endl;
    }
    if(fileStream.fail())
        std::cerr << "Input file stream error bit is set, possible read error on file." << std::endl;               
}

如果您更喜欢 C 文件处理，请尝试

#include <cstdio>

int main(){
    FILE *fid = fopen("/trail","r");
    double trainsample;
    if(fid){
        while(!feof(fid)){
            fscanf(fid,"%lf",&trainsample); // Please notice "lf" when using double. Using "f" will result garbage.
            printf("%lf\n",trainsample);
        }
    }
}

另请参阅cstdio和 ifstream .