C语言 检查 Cython 中的数组中是否存在值
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Check if a value exists in an array in Cython
提问by Jean-Francois Gallant
I want to know how to check if a value or a object exists in an array, like in python:
我想知道如何检查数组中是否存在值或对象，例如在 python 中：
a = [1,2,3,4,5]
b = 4
if b in a:
print("True!")
else:
print("False")
I want to know if something similar already exists in cython. I have a struct object array of pointers; I want to know if the object exists in this array.
我想知道cython中是否已经存在类似的东西。我有一个指针结构对象数组；我想知道该对象是否存在于该数组中。
Like
喜欢
cdef Node *array
array = <Node *>malloc( 5 * cython.sizeof(Node))
for i in range(5):
array[i].index = i
cdef Node test = array[3]
if test in array:
print("True!")
cdef struct Node:
int index
The code above is not correct, but it illustrates what I mean.
上面的代码不正确，但它说明了我的意思。
回答by luser droog
You pretty much have to iterate through the array and check each element.
您几乎必须遍历数组并检查每个元素。
#include <stdbool.h>
bool isvalueinarray(int val, int *arr, int size){
int i;
for (i=0; i < size; i++) {
if (arr[i] == val)
return true;
}
return false;
}
回答by PADYMKO
Try next:
接下来试试：
(read comments and tests for details how it working)
（阅读评论和测试以了解其工作原理）
#include <stdio.h>
#include <assert.h>
/*
Return index an integer number begin from start an array,
otherwise return -1.
*/
int indexOf(int *array, int array_size, int number) {
for (int i = 0; i < array_size; ++i) {
if (array[i] == number) {
return i;
}
}
return -1;
}
// Tests for indexOf()
void test_indexOf() {
int array[10] = {12, 78, -43, 0, 21, 12, 20, -9, 1, -1};
assert(indexOf(array, 10, 12) == 0);
assert(indexOf(array, 10, 0) == 3);
assert(indexOf(array, 10, 2) == -1);
assert(indexOf(array, 10, 43) == -1);
assert(indexOf(array, 10, 11) == -1);
assert(indexOf(array, 10, -1) == 9);
assert(indexOf(array, 10, 1) == 8);
assert(indexOf(array, 10, -2) == -1);
assert(indexOf(array, 10, 3) == -1);
}
int main () {
test_indexOf();
return 0;
}
Notes:
笔记：
Since the C has not support for reload functions, indexOf() will be work only with array type of integer.
The C has not support for determinate length of a pointer of an array. So, you need manually pass size of array.
Testing environment:
由于 C 不支持重新加载函数，因此 indexOf() 将仅适用于整数数组类型。
C 不支持确定数组指针的长度。因此，您需要手动传递数组的大小。
测试环境：
-
——
$ uname -a
Linux wlysenko-Aspire 3.13.0-37-generic #64-Ubuntu SMP Mon Sep 22 21:28:38 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
$ gcc --version
gcc (Ubuntu 4.8.5-2ubuntu1~14.04.1) 4.8.5
