[C / C ++] C _4_ basic data type conversion, the structure parameters, the output format, the main functions, dynamic memory management

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1. Conversion Data Type: (double)

Automatic type conversion

Cast

2. structure: struct, memcpy, memset

The name of the structure, the structure variable name, member variables. The following is a structure variable

name variable structure

to access and use members: In order to access members of the structure, we use the dot operator. That use variable structure member with the other variables the same



array of structures: the structure may be defined as an array variable, there is no difference with other types of array variable nature. The actual structure for the development of an array of small, vector C ++ Standard Library of the container may be completely substituted array structure


pointer structure



replicated structural body



structure as a parameter



enumeration and community structure of these two data do not generally C

3. formatted output: \, snprintf

Formatted output string to



the following three are the same

4.main function parameters: * argv []

Ls command following two parameters, -l * and Book1






envp parameter stored for the current running environment parameter


may be directly input on the command line #env, effects same as above

The dynamic memory management: a null pointer, malloc, free

malloc function

int * pi = malloc (sizeof ( int)) ;, as free function






1. uninitialized pointer variable

is not set null pointer 2. After release