I summarize the commonly used input and output function __ function

(i) standard input and output:

printf ("%d", n);

scanf ("%d", &n);

(ii) file input and output:

fprintf (FIN, "%d", n);/FILE *fin = open ("In.txt", "RB");

FSCANF (Fout, "%d", &n);/FILE *fout = open ("OUT.txt", "WB");

(iii) input and output redirection:

1.freopen ("In.txt", "RB", stdin);

Freopen ("Outin.txt", "WB", stdout);

In C, the use of scanf () and printf () is read and stored from the file

In C + +, the use of CIN and cout is read and stored from the file

2. The standard file input and output in C + + is:

#include <fstream>

using namespace Std;

Ifstream fin ("in.txt");

Ofstream fout ("OUT.txt");

fin>>a>>b;

fout<<a<<b;

(iv) Input output in string

sprintf (CH, "%d", a);/char Ch[max] to ensure that the CH array is large enough

SSCANF (CH, "%d", &a);

(v) Other

(1) fgetc (Fin);//fin is a file pointer

Function: Reads a character from a file and returns an integer

(2) GetChar ();

Function: read a character from standard input, similar to fgetc, but with different input methods.

(3) fgets (CH, MAXN, Fin),//char Ch[max], MAXN read no more than MAXN-1 characters, and then end with a Terminator ' "; FILE *fin;

Function: Read the complete line from the file and read the "\ n" End of the return character.

can also be used as a keyboard input: fgets (Ch,n,stdin); The advantage of using this is to read data of a specified size, avoiding cache overflow problems caused by the gets function receiving a string from stdin without checking the volume of the cache it replicates

(4) gets (CH);//char Ch[max];

Function: Reads a line of strings from the standard input output, can read spaces and TEB, and reads to the carriage return ' \ n ' end. But it does not limit the number of inputs, so it is easy to buffer overflow, not recommended.