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/*这行不?*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>
#define STR "Enter the operation of your choice"
float first(void);
float second (void);
void star (char ch, int num);
void temp (float num);
int main (void)
{
float add,subtract,multiply,divide;
float num,num1;
char ch;
begin: // goto 跳转
star ('-' ,strlen(STR)); // 程序头
printf("%s \n",STR);
printf(" a) add b) subtract \n");
printf(" c) multiply d) divide \n");
printf(" q) quit \n");
star('-',strlen(STR));
while ((ch = getchar()) != 'q')
{
if (isalnum(ch)) // 调用isalnum() 函数
switch(ch)
{
case 'a':
num = num1 = 0;
num = first();
num1 = second();
printf ("%.2f + %.2f = %.2f \n",num,num1,num+num1);
goto begin;
break;
case 'b':
num = num1 = 0;
num = first();
num1 = second();
printf ("%0.2f - %0.2f = %0.2f \n",num,num1,num-num1);
goto begin;
break;
case 'c':
num = num1 = 0;
num = first();
num1 = second();
printf ("%0.2f * %0.2f = %0.2f \n",num,num1,num*num1);
goto begin;
break;
case 'd':
num = num1 = 0;
num = first();
while (num == 0)
num = first();
num1 = second();
while (num1 == 0)
num1 = second();
printf ("%0.2f / %0.2f = %0.2f \n",num,num1,num/num1);
goto begin;
break;
default:
printf ("你的输入有错误,请重新输入 \n");
goto begin;
break;
}
}
printf ("程序退出 \n");
system("PAUSE");
return 0;
}
void star (char ch, int num)
{
int temp;
for (temp = 0; temp < num; temp++) {
putchar(ch);
}
printf ("\n");
}
float first (void)
{
float fir;
char ch;
printf ("Enter first number : ");
while (scanf("%f",&fir) != 1)
{
while ((ch = getchar()) != '\n')
putchar(ch);
printf (" is not an nubmer \n");
printf (" Please enter a number, such as 2.5 . -1.78E8 or 3 \n");
printf ("Enter first number : ");
}
return fir;
}
float second (void)
{
float sec;
char ch;
printf ("Enter second number : ");
while (scanf ("%f",&sec) != 1)
{
while ((ch = getchar()) != '\n')
putchar(ch);
printf (" is not an nubmer \n");
printf (" Please enter a number, such as 2.5 . -1.78E8 or 3 \n");
printf ("Enter first number : ");
}
return sec;
} |
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