删除重复字符

Description  
         给定一个字符串，将字符串中所有和前面重复多余的字符删除，其余字符保留，输出处理后的字符串。需要保证字符出现的先后顺序。
Prototype
         int GetResult(const char *input, char *output)
Input Param 
         input     输入的字符串
Output Param 
         output    输出的字符串
Return Value
         0         成功
         -1        失败及异常

#include <stdlib.h>
#include <stdio.h>
#include <string.h>

int main()
{
int GetResult(const char *, char *);
//char *inCh = "abAdcbad";
char *inCh = "adcdcdcsc";
char OutCh[10] = {0};
int nRst = 0;
nRst = GetResult(inCh, OutCh);
return 0;
}

int GetResult(const char *input, char *output)  
{  
unsigned int i=0;
unsigned int j=0;
unsigned int cnt=0;  
int flag=1;  
unsigned int lenIn=0; 
unsigned int lenOut=0;
//判断输入和输出有效性  
if((input == NULL) || (output == NULL))  
{  
return -1;  
}

lenIn=strlen(input); 

for(i = 0; i<lenIn; i++)  
{  
flag = 1;  
for(j = 0; j < lenOut; j++)  
{  
if(output[j] == input[i])  
flag = 0;  
}  
if(flag)  
{
output[cnt++] = input[i]; 
output[cnt] = '\0';  
lenOut = strlen(output);
} 
} 
output[cnt] = '\0';  
return 0;  
}