Basic knowledge of C language

Hello World

Include file contains commands

<stdio.h> head File/First file

the int main () declares that a name is main, and the type is a function of shaping,

This part is called the function Head section in the function, and there is a main function in each program

The main function is the entry part of a program.

{......} : function Body

Return the end flag of the main function, according to the function header section of the request, the returned data needs to be a shaping data.

/* * * Comment

#include <stdio.h>int  main () {printf ("Hello, world!　　I ' m coming!\n");  return0;}

First Small program

#include <stdio.h>/*Include header file*/#defineHeight 10/* Define Constants */intCalculateintLong,intWidth);/*function Declaration*/intMain ()/*Main function*/{intM_long;/*define shaping variables, representing length*/ 　　 intM_width; intResult/*define shaping variables, representing volume*/printf ("the height of the rectangle is:%d\n", Height);/*Show Hints*/printf ("Please enter the length \ n"); scanf ("%d", &m_long);/*Input Length*/printf ("Please enter the width \ n"); scanf ("%d",&m_width); Result=calculate (M_long,m_width);/*call function, calculate volume*/printf ("the volume of the box is:"); printf ("%d\n", result); return 0; }  intCalculateintLong,intWidth);/*define the calculation volume function*/{intresult=long*width*Height; returnResult/*returns the calculated volume result*/}

Code Execution procedures

1. Start

Include header file = = "Define constant = =" function declaration = = " Enter main function main = =" program End

2. Main function body

Define REQUIRED variable = = "Display message = =" Input calculation condition = = "Calculates the volume of the box and calls the Calculate function.

3. Calculate function Body

Executes the function body code, calculates the result and returns it.

A different place than Python.

#define Height #define定义了一个符号Height, the height in this program represents 10.

int calculate (int Long,int Width);   Function declaration, to prepare for the use of the function below.

int m_width; Define variables to prepare for the use of variables.

scanf ("%d", &m_long);    Enter the statement, &m_long store the input information.

Summarize:

C programs start with the main function, regardless of where they are placed.

C program is not case-sensitive

Each execution statement is ";" End

Basic knowledge of C language