预测分析程序
// Expression.cpp : Defines the entry point for the console application. //
#include "stdafx.h"
#include "conio.h"
#define E 1
#define T 2
#define E_ 3
#define T_ 4
#define F 6
#define digit 7 // 数字
#define add 8 // 左括号
#define mul 9 // 右括号
#define lb 10
#define rb 11
int nStackPtr;
int stack[100]; // 栈
void Push(int n)
{
nStackPtr ++;
stack[nStackPtr] = n;
}
void Pop()
{
nStackPtr--;
}
void PrintStack()
{
int i;
for (i = nStackPtr; i >= 0; i--)
{
if (stack[i] == E) printf("E ");
if (stack[i] == E_ ) printf("E' ");
if (stack[i] == T ) printf("T ");
if (stack[i] == T_ ) printf("T' ");
if (stack[i] == F) printf("F ");
if (stack[i] == digit) printf("digit ");
if (stack[i] == add) printf("+ ");
if (stack[i] == mul) printf("* ");
if (stack[i] == lb) printf("( ");
if (stack[i] == rb) printf(") ");
}
printf("\n");
}
///////////////////////////////////////////////////////////////// // 利用栈来分析表达式串，判定表达式串是否正确 //
///////////////////////////////////////////////////////////////// int main(int argc, char* argv[])
{
char strInput[100]; // 存放表达式串 bool bResult; int nInputPtr; nStackPtr = -1; nInputPtr = 0; bResult = true; // 输入表达式串，存放在 strInput 中 printf("请输入表达式串："); scanf("%s",strInput); Push(E); PrintStack(); while (bResult && nStackPtr >= 0) { switch(stack[nStackPtr]) { case E: if (strInput[nInputPtr] >= '0' && strInput[nInputPtr]
Pop();
Push(T); } else bResult = false; PrintStack(); break; case T: if (strInput[nInputPtr] >= '0' && strInput[nInputPtr]
Push(F); Push(mul); } else bResult = false; PrintStack(); break; case F: if (strInput[nInputPtr] >= '0' && strInput[nInputPtr]= '0' && strInput[nInputPtr]
// } } Pop(); nInputPtr++; } else bResult = false; PrintStack(); break; case lb: if (strInput[nInputPtr] == '(') { Pop(); nInputPtr++; } else bResult = false; PrintStack(); break; case rb: if (strInput[nInputPtr] == ')') { Pop(); nInputPtr++; } else bResult = false; PrintStack(); break; default: bResult = false; break; } if (bResult == false) printf("表达式有问题了\n"); else printf("表达式没问题!!\n"); getch(); printf("Hello World!\n"); return 0;