中缀算式转后缀算式

来源：互联网发布：ubuntu 17.04 openjdk 编辑：程序博客网时间：2024/05/02 00:35
#include<stdio.h>#include<string.h>#include<stdlib.h>#ifndef _Stack_hstruct StackRecord;typedef struct StackRecord *Stack;int IsEmpty(Stack s);int IsFull(Stack s);Stack CreateStack(int MaxElements);void DisposeStack(Stack s);void MakeEmpty(Stack s);void Push(int x,Stack s);int Top(Stack s);void Pop(Stack s);int TopAndPop(Stack s);#endif //head is dummy#define EmptyTOS -1#define MinStackSize 5struct StackRecord{int capacity;int topofstack;int *a;}; int IsEmpty(Stack s){return s->topofstack == EmptyTOS;}int IsFull(Stack s){return s->topofstack == s->capacity -1;}Stack CreateStack(int MaxElements){Stack s;/*if(MaxElements<MinStackSize){printf("Stack size is too small\n");return 0;}*/s = (Stack)malloc(sizeof(struct StackRecord));if(s == NULL){printf("Out of Space!\n");return 0;}s->a = (int *)malloc(sizeof(int)*MaxElements);if(s->a == NULL){printf("Out of Space\n");return 0;}s->capacity = MaxElements;MakeEmpty(s);return s;}void DisposeStack(Stack s){if(s!= NULL){free(s->a);free(s);}}void MakeEmpty(Stack s){s->topofstack = EmptyTOS;}void Push(int x,Stack s){if(IsFull(s))printf("Stack is Full\n");s->a[++s->topofstack] = x;}int Top(Stack s){if(!IsEmpty(s))return s->a[s->topofstack];printf("Stack is Empty\n");return 0;}void Pop(Stack s){if(IsEmpty(s))printf("Stack is Empty\n");else s->topofstack--;}int TopAndPop(Stack s){if(!IsEmpty(s))return s->a[s->topofstack--];printf("Stack is Empty\n");return 0;}int compare(char a,char b){if((a == '+'||a == '-')&&(b == '*'||b == '/'))return -1;else if((a == '*'||a == '/')&&(b == '+'||b == '-'))return 1;else if((a == '*'||a == '/')&&(b == '*'||b == '/'))return 0;else if((a == '+'||a == '-')&&(b == '+'||b == '-'))return 0;else if(b == ')'&&a !='(')return 1;else if(a == '(')return -1;}char *InfixToPostfix(char *express){int len,i,j;char postfix[50],ch;Stack s;len = strlen(express);s = CreateStack(len);for(i = 0,j;i<len;i++){if(express[i]>='0'&&express[i]<='9'||express[i] == '.'){postfix[j++] = express[i];if((express[i+1]<'0' ||express[i+1]>'9')&&express[i+1]!='.')postfix[j++] = ' ';}else {if(express[i] == '+'&&express[i-1]!=')'&&(i == 0||express[i-1]<'0'||express[i-1]>'9'))continue;if(express[i] == '-'&&express[i-1]!=')'&&(i == 0||express[i-1]<'0'||express[i-1]>'9')){postfix[j++] = express[i];    continue;}if(express[i] == '('||IsEmpty(s))Push(express[i],s);/* else if(express[i] == ')'){while(!IsEmpty(s)&&ch = top(s)&&ch!='('){postfix[j++] = ch;postfix[j++] = ' ';pop(s);}pop(s);}*/else {while(!IsEmpty(s)&&(ch =Top(s))!='\0'&&compare(ch,express[i])>=0){Pop(s);postfix[j++] = ch;postfix[j++] = ' ';}if(ch == '('&&express[i] == ')')Pop(s);elsePush(express[i],s);}}}while(!IsEmpty(s)){ch = Top(s);postfix[j++] = ch;postfix[j++] = ' ';Pop(s);}if(postfix[j-1] == ' ')postfix[j-1] = '\0';else postfix[j] = '\0';return postfix;}int main(){char express[21];char *postfix;int i,j,n;scanf("%s",express);postfix = InfixToPostfix(express);printf("%s",postfix);return 0;}
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