用C语言写的表达式计算器源代码

#include
#include
#include
#include

#define MAX 16
#define AGAIN 10
typedef char R_SElemType; //针对运算符//
typedef float D_SElemType; //针对数据//
typedef struct
{
R_SElemType *base;
R_SElemType *top;
int stacksize;
}SqStackR;

typedef struct{
D_SElemType *base;
D_SElemType *top;
int stacksize;
}SqStackD;

void InitStack(SqStackR *S){ //针对运算符堆栈的初始化//
S->base = (R_SElemType *)malloc(MAX * sizeof(R_SElemType));
if (!S->base){
printf("糟糕，出初始存储空间分配失败！");
exit(0);
}
S->top = S->base;
S->stacksize = MAX;
} //初始化堆栈//

void InitStack(SqStackD *S){ //针对数据堆栈的初始化//
S->base = (D_SElemType *)malloc(MAX * sizeof(D_SElemType));
if (!S->base){
printf("糟糕，出初始存储空间分配失败！");
exit(0);
}
S->top = S->base;
S->stacksize = MAX;
} //初始化堆栈//


int StackEmpty(SqStackR *S){ //针对运算符的清空//
if(S->top == S->base)
return 1;
else
return 0;
} //判断是否空栈//


int StackEmpty(SqStackD *S){
if(S->top == S->base)
return 1;
else
return 0;
} //判断是否空栈//

void DestroyStack(SqStackR *S){ //针对字符的清空//
S->top = S->base;
S->stacksize=0;
} //销毁//

void DestroyStack(SqStackD *S){ //针对数据的清空//
S->top = S->base;
S->stacksize=0;
} //销毁//

void Push(SqStackR *S,R_SElemType e){ //针对运算符的入栈//
int T = (int)S->top,B =(int)S->base;
if ((T-B) == S->stacksize)
{
S->base = (R_SElemType *)realloc(S->base ,(S->stacksize + AGAIN)*sizeof(R_SElemType));
if (!S->base)
{
printf("糟糕，堆栈的重新分配失败，悲剧啦！");
exit(0);
}
S->top = S->base + S->stacksize;
S->stacksize = S->stacksize + AGAIN;
}
*(S->top) = e;
S->top++;
} //入栈//

void Push(SqStackD *S,D_SElemType e){ //针对运算符的入栈//
int T = (int)S->top,B =(int)S->base;
if ((T-B) == S->stacksize)
{
S->base = (D_SElemType *)realloc(S->base ,(S->stacksize + AGAIN)*sizeof(D_SElemType));
if (!S->base)
{
printf("糟糕，堆栈的重新分配失败，悲剧啦！");
exit(0);
}
S->top = S->base + S->stacksize;
S->stacksize = S->stacksize + AGAIN;
}
*(S->top) = e;
S->top++;
} //入栈//


char Pop(SqStackR *S){
R_SElemType e;
if (StackEmpty(S))
{
printf("堆栈是空的。");
exit(0);
}
S->top--;
e = *(S->top);
return e;
} //出栈：e返回栈顶元素后，删除栈顶元素//


float Pop(SqStackD *S){
D_SElemType e;
if (StackEmpty(S))
{
printf("堆栈是空的。");
exit(0);
}
S->top--;
e = *(S->top);
return e;
} //出栈：e返回栈顶元素后，删除栈顶元素//


char GetTop(SqStackR *S){
char e;
if (StackEmpty(S))
{
printf("堆栈是空的。");
exit(0);
}
e = *(S->top - 1);
return

e;
} //取栈顶元素//

float GetTop(SqStackD *S){
float e;
if (StackEmpty(S))
{
printf("堆栈是空的。");
exit(0);
}
e = *(S->top - 1);
return e;
} //取栈顶元素//

int Determine(char c){
char ch[7] = {'+','-','*','/','\n','(',')'};
int i;
for (i = 0;i < 7;i++)
{
if(c == ch[i])
return 1;
}
return 0;
} //判断是否为字符//

char OperatorPriority(char top,char c){
char ch;
if (top == '(' && c == ')' ||top == '\n' && c == '\n')
ch = '=';
else
if(top=='+' || top=='-') //栈顶元素为‘+’或‘-’的时候//
switch(c)
{
case '+':
case '-':
case ')':
case '\n': ch = '>'; break;
case '*':
case '/':
case '(': ch = '<';
}
else
if(top=='*' || top=='/') /*栈顶元素为‘*’或‘/’的时候*/
switch(c)
{
case '+':
case '-':
case '*':
case '/':
case ')':
case '\n': ch = '>'; break;
case '(': ch = '<';
}
else
if(top=='(') /*栈顶元素为‘(’的时候*/
switch(c)
{
case '+':
case '-':
case '*':
case '/':
case '(': ch = '<'; break;
case '\n': printf("悲剧，出错啦!------(温馨提示：错误1)\n"); exit(0);
}
else
if(top==')') /*栈顶元素为‘)’的时候*/
switch(c)
{
case '+':
case '-':
case '*':
case '/':
case '\n': ch = '>'; break;
case '(': printf("悲剧出错啦!-------(温馨提示：错误2)\n"); exit(0);
}
else
if(top=='\n') /*栈顶元素为‘#’的时候*/
switch(c)
{
case '+':
case '-':
case '*':
case '/':
case '(': ch = '<'; break;
case ')': printf("悲剧：出错啦!-------(温馨错误3)\n"); exit(0);
}
return ch;
}


float Operate(float a,char r,float b){
float s, d1 = a, d2 = b;
switch(r){
case '+':s = d1 + d2;break;
case '-':s = d2 - d1;break;
case '*':s = d1 * d2;break;
case '/':if(d1 == 0){s = 0; break;} s = d2 / d1;break;
}
return s;
}


float Expression(char c[],SqStackR *S,SqStackD *D){
float a,b,s = 0,e = 1.0;
int i = 0;
char r;
// SqStackR S;
// SqStackD D;
// InitStack(&S);
// Push(&S,'\n');
// InitStack(&D);
i = 0;
while (c[i] != '\n' || GetTop(S) != '\n')
{
if (!Determine(c[i]))
{
if (c[i] >= '0' && c[i] <= '9')
{
s += c[i] - '0';
while(!Determine(c[++i]))
{
if (c[i] != '.')
{
s *= 10; s += c[i] - '0';
}
else
{
while(!Determine(c[++i]))
{
e *= 0.1;
s += (c[i] - '0') * e;
}
break;
}
}
Push(D,s);
s = 0; e = 1.0;
}
else
{
printf(" 好一个悲剧，出错啦!");
return 0;
}
}
else
switch(OperatorPriority(GetTop(S),c[i]))
{

case '<':
Push(S,c[i]);
i++;
break;
case '=':
Pop(S);
i++;
break;
case '>':
r = Pop(S);
a = Pop(D);
b = Pop(D);
Push(D,Operate(a,r,b));
break;
}
}
return (GetTop(D));
}

void main(){
char c[20],x;
int i = 0;
SqStackR S;
SqStackD D;
InitStack(&S);
Push(&S,'\n');
InitStack(&D);
float r = 0;

for (i = 0;i < 20;i++)
{
c[i] = '\n';
}
printf("开始输入啦：\n");
for(i = 0 ; i < 30 ;i++)
{
if((x = getchar())!= 10)
c[i] = x;
else
break;
}
r = Expression(c , &S ,&D);
printf("= %.2f \n",r);
getchar();
}