Eclipse C++ 字符串作为函数参数

Question

我遇到错误函数的问题，它的目的是检查变量，在某些情况下告诉我变量名称及其值。

我想为函数提供值和名称（作为字符串），但我在以某种方式声明字符串时遇到问题 (Eclipse MinGW C++)。

如果有人能指出我的错误或告诉我解决方法，那就太好了！

这是代码：

#include <string>
#include <iostream>

using namespace std;

int *ierr;

std::string(varname); //problem here, doesnt recognize the string

void error(double varvalue, std::string varname)
 {
        if (varvalue == 0 ) {
            *ierr = 11;
            cout << "Error: " << varname << " has an invalid value (equal 0)";
            cout << "Error number " << *ierr << endl;
            return;
        }
        if (varvalue < 0 ) {
            *ierr = 10;
            cout << "Error: " << varname << " has an invalid value (" << varvalue << " , smaller 0)";
            cout << "Error number: " << *ierr << endl;
            return;
        }
 }

int main() {
    int Par = 0;
    error(Par,"Par"); //test variable
}

Answer 1

您没有正确定义字符串值。语法不正确。更严重的是，您声明了一个未初始化的指针 *ierr，它在运行时导致段错误。

I am having a problem with an error function which' purpose it is to check a variable and in a certain case tell me the variables name and its value.

下面的代码将为您完成，但理解 when to use pointers.

很重要

此外，您可能应该稍微阅读 strings 并熟悉字符串定义、复制、初始化等内容。

#include <string>
#include <iostream>

using namespace std;

void error(double varvalue, std::string varname)
 {

        if (varvalue == 0 ) { //if varvalue is equal to 0

            cout << "Error: " << varname << " has an invalid value (equal 0)";
            cout << "Error number " << varvalue << endl;
            return;
        }

        if (varvalue < 0 ) { //if varvalue is less than 0

            cout << "Error: " << varname << " has an invalid value (" << varvalue << " , smaller 0)";
            cout << "Error number: " << varvalue << endl;
            return;
        }

        if (varvalue > 0) { //if varvlue is greater than 0

            cout<<varname<<" has value: "<<varvalue<<endl;

        }
 }

int main() {

    int Par = 10; // Set initial Par value to 10

    error(Par,"Par"); //test variable

}

Eclipse C++ 字符串作为函数参数

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