[栈和队列]从中缀向后缀转换表达式

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define INIT_STACK_SIZE 100
typedef struct
{
char * chOperator;
int dwtop;
}OPND;

void InitStack(OPND *);
char Pop(OPND *);
void Push(OPND *,char );
char GetTop(OPND);

char ComparePri(char op1,char op2);
void printStack(OPND);

char stringBuffer[128] = {'\0'};
char stringValue[128] = {'\0'};
int main()
{
OPND opnd;
int N = 0;
char ch ,*strValue,*strBuffer;
scanf("%d",&N);
getchar();
while(N--){

strValue = stringValue;
strBuffer = stringBuffer;

memset(stringValue,0,128*sizeof(char));
memset(stringBuffer,0,128*sizeof(char));

gets(stringBuffer);
InitStack(&opnd);
Push(&opnd,'#');

ch = *strBuffer++;
while(ch != '#' || GetTop(opnd) != '#'){
if((ch >= 'a' && ch <= 'z')||(ch >= 'A' && ch <= 'Z')) {
*strValue = ch;
strValue++;
ch = *(strBuffer++);
}
else
switch(ComparePri(GetTop(opnd),ch)){
case '<' : Push(&opnd,ch); ch = *(strBuffer++); break;
case '=' : Pop(&opnd);     ch = *(strBuffer++); break;
case '>' : *strValue = Pop(&opnd); strValue++; break;
}
}
puts(stringValue);
}
return 0;
}
void InitStack(OPND *S)
{
S->chOperator = (char *)malloc(INIT_STACK_SIZE * sizeof(char));
if(!S->chOperator) exit(1);
S->dwtop = 0;
}
void Push(OPND *S,char ch)
{
*(S->chOperator + S->dwtop) = ch;
S->dwtop++;
}
char Pop(OPND *S)
{
S->dwtop--;
return *(S->chOperator + S->dwtop);
}
char ComparePri(char op1,char op2)
{
if((op1 == '+' || op1 == '-')&&(op2 == '*' || op2 == '/'))        return '<';
else if((op1 == '(' && op2 == ')')||(op1 == '#' && op2 == '#')) return '=';
else if(op1 == '(' || op1 == '#' || op2 == '(')                 return '<';
else return '>';
}
void printStack(OPND opnd)
{
while(opnd.dwtop){
opnd.dwtop--;
printf("%c",*(opnd.chOperator + opnd.dwtop));
}
}
char GetTop(OPND opnd)
{
return *(opnd.chOperator + opnd.dwtop -1);
}