转换字符串、插入字符的个数

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

#define MAXCOUNT 2*100

char *transformation(char* str)
{
    int len=strlen(str);
    char *buf=new char[len+1];
    
    char *p=str;
    char *q=p+1;
    int count=1;
    while(*q)
    {
        if(*p==*q)
        {
            count++;
            p++;
            q++;
        }else{
            itoa(count,buf,10);
            int nbits=strlen(buf);
            strcat(buf,q);
            *q=0;
            strcat(str,buf);
            q+=nbits;
            p=q;
            q=p+1;
            count=1;
        }
    }
    itoa(count,buf,10);
    strcat(str,buf);
    delete []buf;
    buf=NULL;
    return str;
}

int main()
{
    char str[MAXCOUNT];
    printf("please input a string:");
    scanf("%s",&str);
    char *pstr=transformation(str);
    printf("after transformation:%s\n",pstr); 
    return 0;
}