20190325

Author: Del-te

简易计算器（中缀表达式）.cpp

@@ -0,0 +1,74 @@
+#include <iostream>
+#include <cctype>
+#include <cstring>
+#include <stack>
+using namespace std;
+char calcu[10000];
+stack<char> ope;
+stack<int> num;
+ 
+int calculate(int a, int b, char c){
+    switch (c) {
+        case '+': return a + b; break;
+        case '-': return a - b; break;
+        case '*': return a * b; break;
+        case '/': return a / b; break;
+        default: return -1;
+    }
+}
+int main(){
+    scanf("%s", calcu);
+    int len = (int)strlen(calcu);
+   
+    for(int i = 0; i<len; i++){
+        if(isdigit(calcu[i])){
+            int temp = 0;
+            while(i < len && isdigit(calcu[i])){
+                temp = temp * 10 + calcu[i] - '0';
+                i++;
+            }
+            num.push(temp);
+            i--;
+        }
+        else{
+            if(calcu[i] == ')'){
+                while(ope.top() != '(' && !ope.empty()){
+                    int temp1 = num.top(); num.pop();
+                    int temp2 = num.top(); num.pop();
+                    num.push(calculate(temp2, temp1, ope.top()));
+                    ope.pop();
+                }
+                if(!ope.empty()) ope.pop();
+            }
+            else if(calcu[i] == '(') ope.push(calcu[i]);
+            else if(calcu[i] == '+' || calcu[i] == '-'){
+                while(!ope.empty() && ope.top() != '('){
+                    int temp1 = num.top(); num.pop();
+                    int temp2 = num.top(); num.pop();
+                    num.push(calculate(temp2, temp1, ope.top()));
+                    ope.pop();
+                }
+                ope.push(calcu[i]);
+            }
+            else{
+                while(!ope.empty() && ope.top() != '+' && ope.top() != '-' && ope.top() != '('){
+                    int temp1 = num.top(); num.pop();
+                    int temp2 = num.top(); num.pop();
+                    num.push(calculate(temp2, temp1, ope.top()));
+                    ope.pop();
+                }
+                ope.push(calcu[i]);
+            }
+        }
+    }
+    while(!ope.empty()){
+        int temp1 = num.top(); num.pop();
+        int temp2 = num.top(); num.pop();
+        num.push(calculate(temp2, temp1, ope.top()));
+        ope.pop();
+    }
+    
+    cout<<num.top();
+    system("pause");
+    return 0;
+}