C语言实现输入字符串之后计算结果（十以内）

#define _CRT_SECURE_NO_WARNINGS


#include
#include
#include
#include


#define 输入合法  str1[i]>=48&&str1[i]<=57||str1[i]==42||str1[i]==43||str1[i]==45||str1[i]== 47
#define SIZE 15


char str1[SIZE], str2[SIZE], str3[SIZE];
float str4[SIZE];
int i = 0, j = 0, k = 0;
float a=0,b=0, temp = 0;


void main()
{
gets(str1);


for (i = 0; i < strlen(str1); i++)
{
if (输入合法)
{
if (str1[i] >= 48 && str1[i] <= 57)//找出输入字符串中的数字并存储在数组str2里
{
str2[j] = str1[i];
j++;
}
else if (str1[i] == 42 || str1[i] == 43 || str1[i] == 45 || str1[i] == 47)//找出输入字符串中的运算符号（+、-、*、/）
{
if (k == 0)
{
str3[k] = str1[i];
k++;
}
else
{
if (str1[i] == 42 || str1[i] == 47)//乘法和除法优先级高于加法和减法，直接写入数组str3
{
str3[k] = str1[i];
k++;
}
else if (str1[i] == 43 || str1[i] == 45)//加法和减法需要再作判断
{
if (str3[k - 1] == 43 || str3[k - 1] == 45)
{
str3[k] = str1[i];
k++;
}
else
{
while (str3[k - 1] == 42 || str3[k - 1] == 47)//如果数组str3里最后一个运算符高于加法和减法，则高运算符复制到数组str2中，
{
str2[j] = str3[k - 1];
j++;
k--;
}
str3[k] = str1[i];
k++;
}
}
}
}
}
else
{
goto ERROR;
}
}
for (k =k- 1; k >= 0; k--)
{
str2[j] = str3[k];
//str3[k] = 0;
j++;
}//数组str2="123*45*6++"




for (i = 0, k = 0,j=0; i < strlen(str1); i++)
{
if (str2[i] >= 48 && str2[i] <= 57)//找出输入字符串中的数字并存储在数组str3里
{
str4[k] = str2[i]-48;
k++;
}
else if (str2[i] == 42 || str2[i] == 43 || str2[i] == 45 || str2[i] == 47)//找出输入字符串中的运算符号（+、-、*、/）
{
if (str2[i] == 42)
{
temp = str4[k - 1]  * str4[k - 2];
k = k - 2;
}
else if (str2[i] == 43)
{
temp = str4[k - 1] + str4[k - 2];
k = k - 2;
}
else if (str2[i] == 45)
{
temp = str4[k - 1] - str4[k - 2];
k = k - 2;
}
else if (str2[i] == 47)
{
/*a = str4[k - 1];
b = str4[k - 2];*/
temp = str4[k - 2] / str4[k - 1];
k = k - 2;
}
str4[k] = temp;
k++;
}
}


printf("%.2f\n", temp);


ERROR: printf("errorinput!\n");


system("pause");


}