这个问题看起来与this one非常相似，但是评论中的建议不再有效（如果有的话），如下所示。
我试图编写一个python2-3兼容软件包，其中一个方法中有一个类生成器，而/*
Author: Zachary Alberda
*/
//preprocessor directives and header files
#include <stdio.h>
#define MAX_ARRAY_SIZE 50
//function prototypes separated by data types
void print_array( int array[], int n ); // Print out the array values
void swap( int array[], int index1, int index2 ); // Swap two array elements.
void quicksort( int array[], int low, int high ); // Sorting algorithm
int populate_array( int array[] ); // Fill array with values from user.
int partition( int array[], int low, int high ); // Find the partition point (pivot)
//the main function
int main(void)
{
int array[MAX_ARRAY_SIZE]; //set n = to size of user created size of array
int n = populate_array(array); //print the original array to the screen
print_array(array, n ); //print array of size n
quicksort(array, 0, n-1); //perform the algorithm low is 0, high is size of array -1.
printf("The array is now sorted:\n");//Inform user that the array is sorted.
print_array(array, n);//print the sorted array
return 0; // exit without errors.
}
// *array and array[] are the same...
int populate_array(int array[])
{
int n = -1;//initialize variable n(local variable to function populate_array)
printf("Enter the value of n > ");//inform user of what to input
scanf("%d", &n);
/*
CHECK IF N IS VALID
This is a robust do while loop!
1) Performs the if-statements while 'n' is not valid in a do-while loop.
-The reason I do this is because it will cause errors
if the if-statements are individual without the do-while loop.
2)The program will not crash if you try different combinations
of inputs for 'n'. :)
3)Checks if user input is > MAX_ARRAY_SIZE
4)Checks if user input is < 0
5)Checks if user input is == 0
*/
do
{
if(n > MAX_ARRAY_SIZE)
{
printf("%d exceeds the maximum array size. Please try again.\n\n", n);
printf("Enter the value of n > ");
scanf("%d", &n);
}
else if(n < 0)
{
printf("%d is less than zero. Please try again.\n\n", n);
printf("Enter the value of n > ");
scanf("%d", &n);
}
else if(n == 0)
{
printf("%d Array of size 0? Please don't try this, and... Please try again.\n\n", n);
printf("Enter the value of n > ");
scanf("%d", &n);
}
}while(n <= 0 || n > MAX_ARRAY_SIZE);
//scan in array if user input is valid
for(int i = 0; i < n; i++)
scanf("%d", &array[i]);
printf("The initial array contains: \n");//Inform user of initial array
return n;
}
void print_array(int array[], int n)
{
//print array in pre/post order before and after the algorithm.
for(int i = 0; i < n; i++)
printf("%+5d\n", array[i]);
}
void quicksort(int array[], int low, int high)
{
if (low < high)
{
/* pivot is partitioning index, array[pivot] is now
at right place */
int pivot = partition(array, low, high);
// Separately sort elements before
// partition and after partition
quicksort(array, low, pivot - 1);
quicksort(array, pivot + 1, high);
}
}
int partition(int array[], int low, int high)
{
int pivot = array[high];
int i = low;
for (int j = low; j <= high- 1; j++)
{
// If current element is smaller than or
// equal to pivot
if (array[j] <= pivot)
{
swap(array, i, j);
i = i +1;
}
}
swap(array, i, high);
return i;
}
void swap(int array[], int index1, int index2)
{
//swap positions of array index 1 and 2
int temp = array[index1];
array[index1] = array[index2];
array[index2] = temp;
}
在python-2.7测试中给我带来了问题：
type()Python-Future overview页面上写着：
Python 2.7.13 (default, Mar 18 2017, 17:03:32)
[GCC 4.2.1 Compatible Apple LLVM 7.0.2 (clang-700.1.81)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from __future__ import unicode_literals
>>> from builtins import str
>>> type('MyClass', (object,), {})
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: type() argument 1 must be string, not unicode
>>> type(str('MyClass'), (object,), {})
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: type() argument 1 must be string, not newstr
我预计这会在需要字符串的任何地方给我一致的行为，但显然不是。
正确的，与版本无关的方法是什么？在python-2.6时代，我联系到了另一个问题，从那时起，行为似乎发生了变化。我不认为我可以转储unicode_literals，因为如果我没有调用hashlib，我会遇到可移植性问题（在别处）。
答案 0 :(得分：4)
请勿使用builtins.str()，请使用Python版本附带的普通str：
>>> from __future__ import unicode_literals
>>> type(str('MyClass'), (object,), {})
<class '__main__.MyClass'>
这适用于Python 2和3.如果future.builtins模块默认替换str内置类型，请使用__builtins__模块：
try:
# Python 2
from __builtin__ import str as builtin_str
except ImportError:
# Python 3
from builtins import str as builtin_str
MyClass = type(builtin_str('MyClass'), (object,), {})