C/c++-style Input/Output function

C-style input and output

(1) int getchar () and int putchar (int c)

GetChar reads characters from the stdin input stream and can read only one character at a time. If you want to read multiple characters at once, you can put them in a loop. GetChar reads all types of characters, including spaces.

Putchar prints a character to the screen and prints only one character at a time. For example:

Char A;
while ((A=getchar ()) = ' E ') # #输入流中是一长串的窗口输入, GetChar () reads the characters from the input stream, writes to a, and terminates the loop when the character E is encountered.
Putchar (a); # # The place is also available in printf ("%c", a);

(2) char* gets (char *s) and int puts (const char* s)

The char* gets (char *s) function reads a line from stdin to the cache space that s points to, a new line or EOF symbol as the end of a read.

For example:

Char str[100];

Gets (str);

printf ("\ n you entered:");

Puts (str);

Get (str) can also be used in loops as a criterion. The Std::gets function is also used in C + +, which is deprecated (deprecated, still available) in c++11 and is completely removed from the c++14.

(3) int scanf (const char* format, ...) and int printf (const char* format, ...)

Format can be%s (string),%d (integer),%c (character),%f (floating point), and so on.

SCANF can ignore spaces. scanf ("%d", &a); Cascade Input Mode:

int A, B;

scanf ("%d%d", &a, &b);

This input method can also be used as a criterion for looping, while (scanf ("%d%d", &a, &b)) and the following C + + style input std::cin type, the input data type and the variable declaration type is different, the scanf function returns 0, the loop terminates.

######## #C + + style input and output ###########

The input method is std::cin>> A, and can also be std::cin>>a>>b by cascading input. This input method can ignore spaces.

It is important to note that the resulting input values are very much related to the type of A/b declaration, for example:

int A;

Char b;

cin>>a>>b;

After compiling, load the row, enter 29, 29. Then eventually get the a=29, while the b=2. That is, a is defined as an arithmetic type int,29 input to a, B is defined as a character type, and only the first character 2 is read.

Also pay attention to the return type of cin>>a, for example:

while (Cin>>a)

When the input type is inconsistent with the declaration type of a, Cin>>a returns 0 and jumps out of the while loop. Returns a non-0 value when the input type is consistent, and the loop continues.

Output mode is std::cout<< c<< Endl. Endl for the line, the use is very simple, here do not repeat.

C/c++-style Input/Output function