C++ 从“int”到“const char*”的无效转换
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invalid conversion from 'int' to 'const char*'
提问by GregT
I'm using gccon codeblocks and I'd like to write a function that uses an array of records.
我gcc在代码块上使用，我想编写一个使用记录数组的函数。
However I keep getting the error:
但是我不断收到错误消息：
invalid conversion from 'int' to 'const char*'
The code:
编码：
#include <iostream>
#include <string>
using namespace std;
struct rendeles {
string nev;
int mennyiseg;
};
struct teaceg {
string nev;
int mennyiseg;
};
int szam;
struct rendeles rendelt [100];
struct teaceg cegek [100];
int h;
int hanyadikceg (string cegnev)
{
for (int i=0;i<szam;i++)
{
if (cegek[i].nev==cegnev)
{
return i;
}
}
return -1;
}
int main()
{
cout << "Hány db rendelés lesz ?sszesen?";
cin >> szam;
if (szam > 100)
{
cout << "Hiba: túl nagy a rendelések száma! (100 a maximum)";
return -1;
}
for (int i=0;i<szam;i++)
{
cout << "A(z) " << i+1 <<". cég neve:";
cin >> rendelt[i].nev;
cout << "A(z) " << i+1 <<". rendelés mennyisége:";
cin >> rendelt[i].mennyiseg;
}
cout << endl;
h = hanyadikceg('Lipton'); //the problem is in this line
cout << "Hanyadik cég a xyz:" << h;
for (int i=0;i<szam;i++)
{
cout << "A(z) " << i+1 << ". rendelés: " << rendelt[i].nev << " " << rendelt[i].mennyiseg << endl;
}
return 0;
}
What causes this error?
是什么导致了这个错误？
回答by Oliver Charlesworth
You need to use double-quotes (") for string literals, not single-quotes (').
您需要"对字符串文字使用双引号 ( )，而不是单引号 ( ')。
回答by Moo-Juice
You are using single quotes ('Lipton'). Single quotes are for char-literals.
您正在使用单引号 ( 'Lipton')。单引号用于char-literals。
Use "Lipton", for a const char*literal.
使用"Lipton", 作为const char*文字。
回答by George Skoptsov
Change 'Lipton'to "Lipton"in the problem line and the compilation error will go away.
在问题行中更改'Lipton'为"Lipton"，编译错误将消失。
In C/C++, double-quoted expressions are strings (or, technically, string literals) and resolve to char *or const char *type, while single-quoted expressions are characters (or character literals) and resolve to chartype (which can be implicitly casted to int). That explains your error: the compiler cannot convert the charinteger type to the const char *that the function signature requires.
在 C/C++ 中，双引号表达式是字符串（或者，从技术上讲，字符串文字）并解析为char *或const char *类型，而单引号表达式是字符（或字符文字）并解析为char类型（可以隐式转换为int）。这解释了您的错误：编译器无法将char整数类型转换const char *为函数签名所需的类型。
回答by Lou
h = hanyadikceg('Lipton');
should be
应该
h = hanyadikceg("Lipton");
