char，isnumber方法 [英] char, isnumber method

问题描述

我的代码中有错误，

这是我的代码：

Hi,
I'm having errors in my code below,
This is my code:

#include "stdafx.h"
#include <vector>
#include <iostream>
using namespace std;

int main(){
	vector<int> numbers(0);
	cout << "please enter you numbers :::\n''entering any characters but numbers is the end of entry''";
	char ch;
	int i = 0;
	while (Isnumber(ch)){    //here is the error
		do{
			ch = getchar();
			int newnumber = 0;
			cout << "element(" << i << ") = ";
			cin >> newnumber;
			numbers.push_back(newnumber);
		} while (ch>0 || ch < 9);
	}	
	getchar();
}

两个错误，

它表示标识符未知，

和

它表示变量char是uninitialazed局部变量，

two errors,
it says that identifier is unknown,
and
it says variable char is uninitialazed local variable,

推荐答案

编译器当然是正确的。 C ++ 没有 IsNumber 函数，实际使用 ch uninitialised。

为什么你用 C ++ 流混合 CI / O 电话？

你的意思是：

The compiler is right, of course. C++ has NO IsNumber function, and ch is actually used uninitialised.
Why are you mixing C I/O calls with C++ streams?
Did you mean something like:

#include <iostream>
#include <vector>
using namespace std;

int main()
{
  vector <int> v;
  int i;
  for (;;)
  {
    cout << "please enter a number (any other string to exit): ";
    cin >> i;
    if (!cin.good()) break;
    v.push_back(i);
  }
}

Isnumber确实是一个未知的标识符，拼写为大写I。



ch确实是一个未初始化的变量。您在为其分配值之前使用它。

Isnumber is indeed an unknown identifier, as spelled it with a capital "I".

And ch is indeed an uninitialized variable. You use it before a value is assigned to it.

您正在使用 ch调用 IsNumber（ch） 首次执行代码时未定义。为避免这种情况，您有三种选择：

• 使用执行 ... while loop
• 初始化 ch ，其值为 IsNumber return true
• 重写你的代码是移除外部循环并在内部循环中使用 if 条件来检查数字

You are calling IsNumber(ch) with ch undefined when the code is executed the first time. To avoid this you have three options:

• Use a do ... while loop
• Initialize ch with a value that let IsNumber return true
• Rewrite your code be removing the outer loop and use an if condition in the inner loop to check for numbers

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