Prefix to Postfix 코드인데요 ㅠㅠ

#include <stdio.h>
#include <string.h>
 
#define OPERATORS "+-*/"
 
void preToPostFix(char* preFixIn, char* exprOut);
int findExprLen(char* exprIn);
 
int main(void)
{
	char preFixExpr[256] = "-+*ABC/EF";
	char postFixExpr[256] = "";
 
	preToPostFix(preFixExpr, postFixExpr);
 
	printf("Prefix expr : %-s\n", preFixExpr);
	printf("Post expr : %-s\n", postFixExpr);
 
		return 0;
}//main
 
void preToPostFix(char* preFixIn, char* postFix)
{
 
	char operator [2];
	char postFix1[256];
	char postFix2[256];
	char temp[256];
	int lenPreFix;
 
	if (strlen(preFixIn) == 1)
	{
		*postFix = *preFixIn;
		*(postFix + 1) = '\0';
		return;
	}//if only operand
 
	*operator  =  *preFixIn;
	*(operator + 1) = '\0';
	//find 1st expression
 
	lenPreFix = findExprLen(preFixIn + 1);
	strncpy(temp, preFixIn + 1, lenPreFix);
	*(temp + lenPreFix) = '\0';
	preToPostFix(temp, postFix1);
 
	//Find Second expression
 
	strcpy(temp, preFixIn + 1 + lenPreFix);
	preToPostFix(temp, postFix2);
 
	//Concatenate to postFix
	strcpy(postFix, postFix1);
	strcpy(postFix, postFix2);
	strcpy(postFix, operator);
 
	return;
}//preToPostFix
 
int findExprLen(char* exprIn)
{
	//Local Definitions
	int len1;
	int len2;
 
	if (strcspn(exprIn, OPERATORS) == 0)
		//General Case : First character is operator
		//find length of 1st expression
	{
		len1 = findExprLen(exprIn + 1);
		//find length of 2nd expression
		len2 = findExprLen(exprin + 1 + len1);
	}
	else
		//base case 1st char is operand
		len1 = len2 = 0;
	return len1 + len2 + 1;
}//findExprLen

if (strlen(preFixIn) == 1)
	{
		*postFix = *preFixIn;
		*(postFix + 1) = '\0';
		return;
	}//if only operand
 
	*operator  =  *preFixIn;
	*(operator + 1) = '\0';
	//find 1st expression