内置函数，用于在C中搜索排序数组 [英] Built in function for searching sorted array in C

问题描述

C中是否有内置函数来搜索已排序的整数数组?

Is there a built in function in C for searching an integer array that has been sorted?

我可以很容易地实现它，但是这看起来很普通-如果没有库或内置的C函数会很奇怪.

I can easily implement it but it seems like such a common thing - would be weird if there is no library/built in C function.

推荐答案

在排序数组bsearch()用于二进制搜索="nofollow noreferrer"> https://www.tutorialspoint.com/c_standard_library/c_function_bsearch.htm

There is bsearch() for binary search in sorted array https://www.tutorialspoint.com/c_standard_library/c_function_bsearch.htm

示例:

#include <stdio.h>
#include <stdlib.h>


int cmp_int(const void *pa, const void *pb) { 
    int a = *(int *)pa; 
    int b = *(int *)pb; 
    return (a > b) - (a < b); 
}

int values[] = { 5, 20, 29, 32, 63 };

int main () {
    int *item;
    int key = 32;

    /* using bsearch() to find value 32 in the array */
    item = (int*) bsearch (&key, values, 5, sizeof (int), cmpfunc);
    if( item != NULL ) {
        printf("Found item = %d\n", *item);
    } else {
        printf("Item = %d could not be found\n", *item);
    }

    return(0);
}

UPD 通过@ jonathan-leffler添加了适当的比较器

UPD Added proper comparer by @jonathan-leffler

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