cin函数测试有问题！！！仅供参考！！！
(有bug)各个函数的读入速度
整数和字符
cpu:i7-7700HQ g++ 6.3.0
| 名称 | 10^5整数 | 10^6整数 | 10^7整数 | 10M字符串 |
|---|---|---|---|---|
| fin | 66毫秒 | 692毫秒 | 6831毫秒 | 117毫秒 |
| 108毫秒 | 45毫秒 | 425毫秒 | ||
| cin关同步 | 76毫秒 | 40毫秒 | 397毫秒 | 77毫秒 |
| scanf | 29毫秒 | 287毫秒 | 2838毫秒 | 75毫秒 |
| FILE* fscanf | 29毫秒 | 280毫秒 | 2818毫秒 | 68毫秒 |
| 快读 | 4毫秒 | 44毫秒 | 463毫秒 |
代码
#include <iostream>
#include <fstream>
#include <cstdio>
#include <ctime>
using namespace std;
char s[10000005];
int x[10000005];
void tfst(string name, int n)
{
ifstream fin(name.c_str());
for (int i = 0; i <= n; i++)
fin >> x[i];
fin.close();
}
void tfsts(string name)
{
ifstream fin(name.c_str());
fin >> s;
fin.close();
}
void tfreSan(string name, int n)
{
freopen(name.c_str(), "r", stdin);
for (int i = 0; i <= n; i++)
scanf("%d", &x[i]);
fclose(stdin);
}
void tfresSan(string name)
{
freopen(name.c_str(), "r", stdin);
scanf("%s", s);
fclose(stdin);
}
void tfreFSan(string name, int n)
{
FILE *fin;
fin = fopen(name.c_str(), "r");
for (int i = 0; i <= n; i++)
fscanf(fin, "%d", &x[i]);
fclose(fin);
}
void tfresFSan(string name)
{
FILE *fin;
fin = fopen(name.c_str(), "r");
fscanf(fin, "%s", s);
fclose(fin);
}
void tfreCin(string name, int n)
{
freopen(name.c_str(), "r", stdin);
for (int i = 0; i <= n; i++)
cin >> x[i];
fclose(stdin);
}
void tfresCin(string name)
{
freopen(name.c_str(), "r", stdin);
cin >> s;
fclose(stdin);
}
void tfreCinS(string name, int n)
{
freopen(name.c_str(), "r", stdin);
std::ios::sync_with_stdio(false);
for (int i = 0; i <= n; i++)
cin >> x[i];
std::ios::sync_with_stdio(true);
fclose(stdin);
}
void tfresCinS(string name)
{
freopen(name.c_str(), "r", stdin);
std::ios::sync_with_stdio(false);
scanf("%s", s);
std::ios::sync_with_stdio(true);
fclose(stdin);
}
inline int qr()
{
int data = 0, k = 1;
char c;
for (c = getchar(); (c > '9' || c < '0') && c == '-'; c = getchar())
if (c == '-')
k = -1;
for (; '0' <= c && c <= '9'; c = getchar())
data = data * 10 + c - '0';
return data * k;
}
void makeInt(string name, int n)
{
ofstream fout(name.c_str());
for (int i = 1; i <= n; i++)
fout << rand() << " ";
fout.close();
}
void tq(string name, int n)
{
freopen(name.c_str(), "r", stdin);
for (int i = 0; i <= n; i++)
x[i] = qr();
fclose(stdin);
}
void makeChar(string name)
{
freopen(name.c_str(), "w", stdout);
for (int i = 1; i <= 10000000; i++)
putchar('%');
fclose(stdout);
}
int main()
{
srand(time(0));
int st, et;
makeInt("d1.in", 100000);
makeInt("d2.in", 1000000);
makeInt("d3.in", 10000000);
makeChar("d4.in");
freopen("out.txt", "w", stdout);
st = clock();
tfst("d1.in", 100000);
et = clock();
cout << "fin 10^5耗时" << (double)(et - st) / CLOCKS_PER_SEC * 1000 << "毫秒" << endl;
st = clock();
tfst("d2.in", 1000000);
et = clock();
cout << "fin 10^6耗时" << (double)(et - st) / CLOCKS_PER_SEC * 1000 << "毫秒" << endl;
st = clock();
tfst("d3.in", 10000000);
et = clock();
cout << "fin 10^7耗时" << (double)(et - st) / CLOCKS_PER_SEC * 1000 << "毫秒" << endl;
st = clock();
tfsts("d4.in");
et = clock();
cout << "fin 10M耗时" << (double)(et - st) / CLOCKS_PER_SEC * 1000 << "毫秒" << endl;
st = clock();
tfreCin("d1.in", 100000);
et = clock();
cout << "cin 10^5耗时" << (double)(et - st) / CLOCKS_PER_SEC * 1000 << "毫秒" << endl;
st = clock();
tfreCin("d2.in", 1000000);
et = clock();
cout << "cin 10^6耗时" << (double)(et - st) / CLOCKS_PER_SEC * 1000 << "毫秒" << endl;
st = clock();
tfreCin("d3.in", 10000000);
et = clock();
cout << "cin 10^7耗时" << (double)(et - st) / CLOCKS_PER_SEC * 1000 << "毫秒" << endl;
st = clock();
tfresCin("d4.in");
et = clock();
cout << "cin 10M耗时" << (double)(et - st) / CLOCKS_PER_SEC * 1000 << "毫秒" << endl;
st = clock();
tfreCinS("d1.in", 100000);
et = clock();
cout << "cin sync_with_stdio(false) 10^5耗时" << (double) (et - st) / CLOCKS_PER_SEC * 1000 << "毫秒" << endl;
st = clock();
tfreCinS("d2.in", 1000000);
et = clock();
cout << "cin sync_with_stdio(false) 10^6耗时" << (double) (et - st) / CLOCKS_PER_SEC * 1000 << "毫秒" << endl;
st = clock();
tfreCinS("d3.in", 10000000);
et = clock();
cout << "cin sync_with_stdio(false) 10^7耗时" << (double) (et - st) / CLOCKS_PER_SEC * 1000 << "毫秒" << endl;
st = clock();
tfresCinS("d4.in");
et = clock();
cout << "cin sync_with_stdio(false) 10M耗时" << (double) (et - st) / CLOCKS_PER_SEC * 1000 << "毫秒" << endl;
st = clock();
tfreSan("d1.in", 100000);
et = clock();
cout << "scanf 10^5耗时" << (double)(et - st) / CLOCKS_PER_SEC * 1000 << "毫秒" << endl;
st = clock();
tfreSan("d2.in", 1000000);
et = clock();
cout << "scanf 10^6耗时" << (double)(et - st) / CLOCKS_PER_SEC * 1000 << "毫秒" << endl;
st = clock();
tfreSan("d3.in", 10000000);
et = clock();
cout << "scanf 10^7耗时" << (double)(et - st) / CLOCKS_PER_SEC * 1000 << "毫秒" << endl;
st = clock();
tfresSan("d4.in");
et = clock();
cout << "scanf 10M耗时" << (double)(et - st) / CLOCKS_PER_SEC * 1000 << "毫秒" << endl;
st = clock();
tfreFSan("d1.in", 100000);
et = clock();
cout << "FILE* fscanf 10^5耗时" << (double)(et - st) / CLOCKS_PER_SEC * 1000 << "毫秒" << endl;
st = clock();
tfreFSan("d2.in", 1000000);
et = clock();
cout << "FILE* fscanf 10^6耗时" << (double)(et - st) / CLOCKS_PER_SEC * 1000 << "毫秒" << endl;
st = clock();
tfreFSan("d3.in", 10000000);
et = clock();
cout << "FILE* fscanf 10^7耗时" << (double)(et - st) / CLOCKS_PER_SEC * 1000 << "毫秒" << endl;
st = clock();
tfresFSan("d4.in");
et = clock();
cout << "FILE* fscanf 10M耗时" << (double)(et - st) / CLOCKS_PER_SEC * 1000 << "毫秒" << endl;
st = clock();
tq("d1.in", 100000);
et = clock();
cout << "快读 10^5耗时" << (double)(et - st) / CLOCKS_PER_SEC * 1000 << "毫秒" << endl;
st = clock();
tq("d2.in", 1000000);
et = clock();
cout << "快读 10^6耗时" << (double)(et - st) / CLOCKS_PER_SEC * 1000 << "毫秒" << endl;
st = clock();
tq("d3.in", 10000000);
et = clock();
cout << "快读 10^7耗时" << (double)(et - st) / CLOCKS_PER_SEC * 1000 << "毫秒" << endl;
return 0;
}写在最后
其他人测的结果：“cin总是最慢的，cin关同步和scanf差不多”。
总之。。。
快读大fa好orz。
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