我正在嘗試制作一個 function 將 integer 轉換為不返回字符串的字符串。 我該如何解決這個問題？

Question

我正在嘗試使用此代碼將整數轉換為字符串它正在打印值但沒有向調用 function 返回任何內容

char* itoa(int num, int num_len)
{
    char str[num_len+2];
    int i;
    //if the num is 0
    if(num == 0)
        strcpy(str, "0");
    //if the num is negetive then we append a '-' sign at the beginning
    //and put '\0' at (num_len+1)th position 
    else if(num < 0)
    {
        num *= -1;
        str[num_len+1] = '\0';
        str[0] = '-';
        i = num_len+1;
    }
    //we put '\0' (num_len)th position i.e before the last position
    else
    {
        str[num_len] = '\0';
        i = num_len;
    } 

    for(;num>0;num/=10,i--)
    {
        str[i] = num%10 + '0';
        printf("%c ",str[i]);//for debugging
    }

    return str;
}

Answer 1

我只是忘記了那個規則。 非常感謝您

char* itoa(int num, int num_len,char* str)
{
    int i;
    str = (char*)malloc((num_len + 2)*sizeof(char)); 
    if(num == 0)
        strcpy(str, "0");
    else if(num < 0)
    {
        num *= -1;
        str[num_len+1] = '\0';
        str[0] = '-';
        i = num_len;
    }
    else
    {
        str[num_len] = '\0';
        i = num_len-1;
    } 

    for(;num>0;num/=10,i--)
    {
        str[i] = num%10 + '0';
        printf("%c ",str[i]);
    }

    return str;
}