Question

int _tmain(int argc, _TCHAR* argv[])
{
    //timer1();
    cout.precision(30);

    char coordinates[100]="-88.5652389526367,39.1187744140625,0";
    char* chars_array_coordinates=strtok(coordinates,",");
    cout<<"chars_array_coordinates"<<chars_array_coordinates<<"\n";
    char* chars_array_coordinates_1=strtok(NULL,",");
    cout<<"chars_array_coordinates"<<chars_array_coordinates_1<<"\n";

    float coordinates_Latitude=atof(chars_array_coordinates);
    cout<<"coordinates_Latitude"<<coordinates_Latitude<<"\n";
    float coordinates_Latitude_1=atof(chars_array_coordinates_1);
    cout<<"coordinates_Latitude_1"<<coordinates_Latitude_1<<"\n";
}

输出

chars_array_coordinates=-88.5652389526367
chars_array_coordinates=39.1187744140625
coordinates_Latitude=-88.565238952636705
coordinates_Latitude=-39.1187744140625

要浮动的字符串：-88.5652389526367到-88.565238952636705＆lt; - 该数字最后可能突然变为'05'。会发生什么？

Answer 1

如上所述，浮点数是近似值。使用它们时可能会失去精度。您必须阅读What Every Computer Scientist Should Know About Floating-Point Arithmetic

实际上，当编译或解释代码时，您的“0.1”已经四舍五入到该格式中最接近的数字，即使在计算发生之前也会导致小rounding error。

为避免此问题，您可以更好地使用小数或双倍。

c ++浮动小数位，这个数字可能会突然出现＆＃39; 05＆＃39;在末尾

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