用C语言实现字符数组转换为16进制数组

int main()
{
    char strarr[20] = {0};
    char hexarr[20] = {0};
    strcpy(strarr, "helloworld");

    char ch;
    char arr[3]={0};
    int i = 0;

    for(i = 0; i < strlen(strarr); i++)
    {
        ch = strarr[i];
        sprintf(arr,"%x",ch);
        strcat(hexarr, arr);
        memset(arr,0,3);
    }

    printf("strlen : %d\r\n", strlen(hexarr));
    printf("sizeof : %d\r\n", sizeof(hexarr));
    printf("hexarr : %s\r\n", hexarr);

}