“setprecision”不是“std”的成员

Posted 2023-02-22

【中文标题】“setprecision”不是“std”的成员

【英文标题】：‘setprecision’ is not a member of ‘std’

【发布时间】：2012-09-17 05:28:42

【问题描述】：

错误：

~> g++ ssstring.cpp
ssstring.cpp: In function ‘int main()’:
ssstring.cpp:12:31: error: ‘setprecision’ is not a member of ‘std’
ssstring.cpp:12:52: error: ‘numeric_limits’ is not a member of ‘std’
ssstring.cpp:12:74: error: expected primary-expression before ‘float’
ssstring.cpp:13:30: error: ‘setprecision’ is not a member of ‘std’
ssstring.cpp:13:51: error: ‘numeric_limits’ is not a member of ‘std’
ssstring.cpp:13:73: error: expected primary-expression before ‘float’
ssstring.cpp:14:28: error: ‘setprecision’ is not a member of ‘std’
ssstring.cpp:14:49: error: ‘numeric_limits’ is not a member of ‘std’
ssstring.cpp:14:71: error: expected primary-expression before ‘float’
anisha@linux-trra:~>

代码：

#include <sstream>
#include <iostream>
#include <string.h>

int main ()

    // Convert `lat`, `lons`, and `vehicleId` to string.
    float selectedPointLat = 2.2;
    float selectedPointLng = 2.3;
    float vehicleId        = 1.0;

    std :: stringstream floatToStringLat, floatToStringLng, floatToStringVehicleId;

    floatToStringLat       << std :: setprecision (std :: numeric_limits<float> :: digits10 + 1); floatToStringLat  << selectedPointLat;
    floatToStringLng       << std :: setprecision (std :: numeric_limits<float> :: digits10 + 1); floatToStringLng << selectedPointLng;
    floatToStringVehicleId << std :: setprecision (std :: numeric_limits<float> :: digits10 + 1); floatToStringVehicleId << vehicleId;

【问题讨论】：

不包括string.h...你的意思是string还是cstring？

顺便说一句，<limits> 需要 std::numeric_limits。

请记住，您可以通过在 C++ 参考中查找标题来找到它们：setprecision、numeric_limits。

【参考方案1】：

您需要为std::setprecision 包含标题<iomanip>，为std::numeric_limits 包含<limits>。这些引用告诉您要包​​含哪个标头。