Dark Horse Programmer----C Language Basic grammar

C Language Basic Grammar

C programs are made up of functions.

The entrance to the C program is a function called Main, referred to as the main function.

Regardless of the number of functions in the program, the main function is executed first.

1 #include <stdio.h> 23int main (void)  45
    {  67return0;  89 } 　　 　　 　　 　　

1. Writing

2. Compile the Cc-c file name. C Generate. o File

3. link cc file name. o //2, 3 combined: CC file name. c-o File name

4. Run./a.out //./File name

Keywords in the C language

The keyword is the C language provides a special meaning of the symbol

The C language provides a total of 32 keywords, all of which are given special meanings in C language, all lowercase.

Auto double int struct break else long switch case enum register

typedef char extern return Union const float Short unsigned continue

For signed void default goto sizeof volatile does if while static

Identifiers in the C language

Some special symbols and names that are customized in the program

Naming rules (be sure to follow)

There can be only 26 characters of the English characters, 10 Arabic numerals 0~9, and the underscore _ composition.

Strictly case-sensitive, such as test and test are 2 different identifiers

Cannot start with a number

You cannot use a keyword as an identifier

Comments in the C language

1  // single-line comment, comment behind program 2 3 /* can be used for single-line or multiline comments, or for middle    -code annotations */ 　　　 　　 　　

Constants in the C language

int integer 4-byte

Char character type 1 bytes

float single-precision floating point 4 bytes

Double Dual-precision floating-point 8 bytes

Variable output in C language

%d output integer variable

%f Output decimal default 6 bit %.3f specify reserved decimal places

%c Output character

Memory analysis of variables in C language

&a Get the memory address of a

1) memory addressing is a large direct-to-variable with large-to-small priority allocation of memory addresses

2) The more the variable is defined, the greater the memory address

3) Get variable address:& variable name

4) Output Address:%p

5) variables must be initialized before they can be used

1 printf ("A's address is:%p\n" , &a);

scanf function　

1 scanf ("%d", &a);  //  can only receive variable address 2    //　　 3 scanf ("%d,%d", &a,&b);    //  quotation mark How to write the input when you write a    space, you can use tab and enter　　 　　　　　　　　　　　　　　　 　　　

Although have already learned C language, but this again let me pick up a lot of knowledge points, learn the time to feel skilled, often will be small details of small principles to ignore, will only use do not know how the situation also occurred, before remember the note lost, but this review will certainly be more skilled, Suggest everyone to lay a good foundation, and often look at their own study notes, are very useful to themselves, refueling!

Dark Horse Programmer----C Language Basic grammar