c++常用函数对应的头文件

持续更新：遇到的时候就记录一下
abs() fabs() 
#include <cmath>
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pow() 幂指函数：//pow(x,y);其作用是计算x的y次方。
#include <cmath>
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floor() ceil() 上下取整
#include <cmath>
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max() min() swap() 
#include <iostream>
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isalpha()
isdigit()
isalnum()
islower()
isupper()
isspace() 判断是否标准空白字符
tolower() 原参数不改变，返回参数转换大小写
toupper() 
#include <cctype>
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exit()
malloc()
calloc()
free()
qsort()
#include <cstdlib>
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sort()
find()
count()
search()
reverse()
lower_bound()
upper_bound()
push_heap()
pop_heap()
make_heap()
sort_heap()
next_permutation()
prev_permutation()
#include<algorithm>

STL string 参考博客：https://blog.csdn.net/u013046610/article/details/72674185