如何使用atoi函数

[cookies08]

首先大家别笑话我，我刚接触VC++没一个星期，写了如下代码，但是用户输入非数字的时候会刷屏，考虑的结果是使用atoi转换过来应该能解决，但不知如何实现？还有在while循环里我想插入一个用户接口，当用户输入X的时候程序则退出，如何实现？

谢谢了

#include "windows.h"
#include "IOSTREAM.h"
#include <stdlib.h>


void Calc(float a,char oper,float b)

{

switch (oper)
{
case '+':
{
cout<<a<<oper<<b<<"的结果为:"<<a+b<<endl;
break;

}
case '-':
{
cout<<a<<oper<<b<<"的结果为:"<<a-b<<endl;
break;
}
case '*':
{
cout<<a<<oper<<b<<"的结果为:"<<a*b<<endl;
break;
}
case '/':
{
if (b!=0)
{
cout<<a<<oper<<b<<"的结果为:"<<a/b<<endl;
}
else cout<<"错误,除数不能为0"<<endl;
break;
}
default:
cout<<"请输入正确的数学计算题"<<endl;
break;
}


}
int main()
{
cout<<"欢迎使用计算器,请输入计算题目,例如1+1"<<endl;
cout<<"\n";

float a,b;
char oper;

while(1)
{

cout<<"请输入"<<endl;
cin>>a>>oper>>b;
Calc(a,oper,b);
cout<<"\n";

}


return 0;
}

[jyh_baoding]

不错，帮顶，ATOI看参数

[mcaok]

int　atoi(const char *nptr);
用法
int n;
char *str = "12345.67";
n = atoi(str);

[哈利路亚1874]

找个地方直接判断输入的是不是X，然后调用exit(0)就可以了

[lsvine]

好好学 加油

问题上面都回答了

[maomaoxiong]

atof, atoi, _atoi64, atol
Convert strings to double (atof), integer (atoi, _atoi64), or long (atol).

Example

/* ATOF.C: This program shows how numbers stored
* as strings can be converted to numeric values
* using the atof, atoi, and atol functions.
*/

#include <stdlib.h>
#include <stdio.h>

void main( void )
{
char *s; double x; int i; long l;

s = " -2309.12E-15"; /* Test of atof */
x = atof( s );
printf( "atof test: ASCII string: %s\tfloat: %e\n", s, x );

s = "7.8912654773d210"; /* Test of atof */
x = atof( s );
printf( "atof test: ASCII string: %s\tfloat: %e\n", s, x );

s = " -9885 pigs"; /* Test of atoi */
i = atoi( s );
printf( "atoi test: ASCII string: %s\t\tinteger: %d\n", s, i );

s = "98854 dollars"; /* Test of atol */
l = atol( s );
printf( "atol test: ASCII string: %s\t\tlong: %ld\n", s, l );
}


Output

atof test: ASCII string: -2309.12E-15 float: -2.309120e-012
atof test: ASCII string: 7.8912654773d210 float: 7.891265e+210
atoi test: ASCII string: -9885 pigs integer: -9885
atol test: ASCII string: 98854 dollars long: 98854

善用MSDN，呵呵~~

[jsit123]

ding...