万能头文件 #include<bits/stdc++.h>
floor(x)向下取整,返回一个<=x的int整型。ceil(x)向上取整,返回一个>=x的int整型。
PI
const double PI = atan(1.0)*4;const double PI = acos(-1.0);
四舍五入
cout << floor(resu+0.5) <
头文件在#include<limits.h>中,直接#include<bits/stdc++.h>也可
cout<<"INT_MAX="<<INT_MAX<<endl<<"ULONG_MAX="<<ULONG_MAX<<endl<<"LONG_MAX="<<LONG_MAX<<endl;输入挂之二
inline int getin() { int ans=0;char tmp; while(!isdigit(tmp=getchar())); do ans=(ans<<3)+(ans<<1)+tmp-'0'; while(isdigit(tmp=getchar())); return ans; }string 出现的问题
#includeusing namespace std;int main(){ string st; cin>>st; int i = st.size(); printf("str size is:%d\n",i); i = strlen(st.c_str()); printf("str size is:%d(by strlen)\n",i); return 0; }
()
记录函数运行时间
#include#include using namespace std; int main(){ clock_t startTime,endTime; startTime = clock(); for (int i = 0; i < 10000000; i++) { i++; } endTime = clock(); cout << "Totle Time : " <<(double)(endTime - startTime) / CLOCKS_PER_SEC << "s" << endl; return 0;}