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main.c

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+#include <stdio.h>
+// 加法函数
+double add(double a, double b)
+{
+    return a+b;
+}
+// 减法函数
+double subtract(double a, double b)
+{
+    return a-b;
+}
+// 乘法函数
+double multiply(double a, double b)
+{
+    return a*b;
+}
+// 除法函数
+double divide(double a, double b)
+{
+    if(b == 0)
+    {
+        printf("Error: 被除数不能为零!\n");
+        return 0;
+    }
+    else
+    {
+        return a/b;
+    }
+}
+// 求模函数
+int mod(int a,int b)
+{
+    if(b==0)
+    {
+        printf("Error: 被除数不能为零!\n");
+        return 0;
+    }
+    else
+    {
+        return a%b;
+    }
+}
+int main()
+{
+    double a, b, result;
+    char operator;
+    printf("请输入所要计算的式 (eg:1 + 2): ");
+    scanf("%lf%c%lf",&a,&operator,&b);
+    switch (operator)
+    {
+        case '+':
+            result=add(a,b);
+            break;
+        case '-':
+            result=subtract(a,b);
+            break;
+        case '*':
+            result=multiply(a,b);
+            break;
+        case '/':
+            result=divide(a,b);
+            break;
+        case '%':
+            result=mod((int)a,(int)b);
+            break;
+        default:
+            printf("Error:请重新输入!\n");
+            return 1;
+    }
+    printf("结果为：%.2lf",result);
+    return 0;
+}