ACM Trick点&&常用操作记录(持续更新)（I\O）

I\O

Fast_In

//从文件读
//注意和ios::sync_with_stdio(false);冲突
typedef long long LL;
namespace fastIO {
#define BUF_SIZE 100000
//fread -> read
bool IOerror = 0;
inline char nc() {
static char buf[BUF_SIZE], *p1 = buf + BUF_SIZE, *pend = buf + BUF_SIZE;
if(p1 == pend) {
p1 = buf;
pend = buf + fread(buf, 1, BUF_SIZE, stdin);
if(pend == p1) {
IOerror = 1;
return -1;
}
}
return *p1++;
}
inline bool blank(char ch) {
return ch == ' ' || ch == '\n' || ch == '\r' || ch == '\t';
}
inline void read(int &x) {
char ch;
while(blank(ch = nc()));
if(IOerror)
return;
for(x = ch - '0'; (ch = nc()) >= '0' && ch <= '9'; x = x * 10 + ch - '0');
}
#undef BUF_SIZE
};
using namespace fastIO;

整行字符串的读入

cin.getline(str,50)

getline(cin,s)

#include<bits/stdc++.h>
using namespace std;

char str[50];

int main()
{
//freopen("in.txt","r",stdin);
while(cin.getline(str,50)){//注意由于用流 当数据很多时较慢
printf("%s\n",str);
}
return 0;
}

#include<bits/stdc++.h>
using namespace std;

string s;

int main()
{
//freopen("in.txt","r",stdin);
while(getline(cin,s)){
cout<<s<<endl;
}
return 0;
}

char[]和string之间的转换

#include<bits/stdc++.h>
using namespace std;

char str[50];
string s;

int main()
{
//string 转 char[]
cin>>s;
strcpy(str,s.c_str());//速度较快
printf("%s\n",str);
return 0;
}

#include<bits/stdc++.h>
using namespace std;

char str[50];
string s;

int main()
{
//char[] 转 string
scanf("%s",str);
s=str;
cout<<s<<endl;
return 0;
}

统计每行文本单词总个数(流方法)

#include<bits/stdc++.h>
#include<sstream>
using namespace std;

char str[50];

int main()
{
freopen("in.txt","r",stdin);
int cnt=0;
while(cin.getline(str,50)){
stringstream ss(str);
char tmp[50];
while(ss>>tmp) cnt++;
}
cout<<cnt<<endl;
return 0;
}

#include<bits/stdc++.h>
#include<sstream>
using namespace std;

string s;

int main()
{
freopen("in.txt","r",stdin);
int cnt=0;
while(getline(cin,s)){
stringstream ss(s);
string tmp;
while(ss>>tmp) cnt++;
}
cout<<cnt<<endl;
return 0;
}