04-07输出字符串为10进制数字

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

int my_hex(const int*sp)//16进制
{
    int sum=0;
    while(isdigit(*sp))
    {
        int x=0;
        if(isdigit(*sp)
        {
            x=*sp-'0';
        }
        else
        {
            char c=tolower(*sp);
            x=c-'a';
        }
        sum=sum*16+x;
        ++sp;
    }
    return sum;
}
int my_oct(int *sp)//8进制
{
    int sum=0;
    while(isdigit(*sp)&&*sp!='8'&&*sp!='9')
    {
        sum=sum*8+*sp-'0';
        ++sp;
    }
    return sum;
}

int my_atoi(const char*sp)
{
int sum=0;
if(sp==nullptr) return sum;
int tag=0;  //1负数，0正数
while(isspace(*sp))++sp; //跳过空格，制表符等空字符
if(*sp=='-')
{
    tag=1;
    ++sp;
}
if(*sp=='+')
{
    tag=0;
    ++sp;
}
if(*sp=='0')
{
    if((*(sp+1))=='x'||(*(sp+1))=='X')
    {
        sum=my_hex(sp+2);   //16进制
    }
    else
    {
        sum=my_oct(sp+1);   //8进制
    }
}
if(tag)
{
    sum=-sum;
}
return sum;
int main()
{
    const char* str[]={"12321",
                        "0123",
                        "0x2a4f",
                        "   -232",
                        "    +234 234",
                        "24323.344",
                        "111112111",
                        "22222222222",
                        "33333333333333"
                        };
    int n=sizeof(str)/sizeof(str[0]);
    for(int i=0;i<n;++1)
    {
        printf("%s==>%d",str[i],my_atoi(str[i]));
    }
    return 0;
}