Set sail, C language basic content finishing

I. Concept and basic format

Program: A collection of ordered commands written to solve a problem.

Algorithm: The specific methods and steps to solve the problem.

Flowchart is a graphical representation of the algorithm. Flowcharts can be intuitive, clear, and more conducive to people to design and understand the algorithm.

Basic structure of C language

#include <stdio.h>

void Main ()

{

printf ("Hello world\n");

}

C comments in the language:

// single-line comment

/*

Multi-line comments

*/

#include <stdio.h>

void Main ()

{

printf ("Hello World");

}

Example:

#include <stdio.h>
void Main ()
{
/*
printf ("**************************************\n");
printf ("Result sheet \ n");
printf ("**************************************\n");
printf ("Name language math English sports \ n");
printf ("Zhang 110 \ n");
printf ("Li 211 one-by-one \ n");
printf ("King 311");
printf ("Zhao 411 one-by-one \ n");
*/
printf ("**************************************\n");
printf ("\ t \ t performance table \ n");
printf ("**************************************\n");
printf ("name \ t language \ t math \ t english \ t sports \ n");
printf ("Zhang \t10\t10\t10\t10\n");
printf ("Lee \t11\t11\t11\t11\n");
printf ("Wang San \t11\t11\t11\t11\n");
printf ("Zhao four \t11\t11\t11\t11\n");
}

Ii. variables and data types

Declaring variables:

Data type variable name = value;

Example: int num = 5

You can also declare multiple variables at once (in the middle, separated):

int num = 5, i = 3;

The use of variables needs to be satisfied: First declare, then assign, then use.

int A;

a=10;

int a=10;

Declare first, then assign value

Naming conventions for identifiers: see Names and meanings

1, there are letters, numbers and underscores, cannot have other special characters, can not start with a number.

2. Reserved keywords cannot be used.

3, strictly case-sensitive. Boy and boy are two variables.

4, it is suggested to use the Hump name method: The first word lowercase, the other words of the first letter capital (EmployeeName).

Data type: Numeric, non-numeric (char);

Value: integer, floating point type;

Integral type: short, integer (int), long integer type (long);

FLOAT: single-precision floating-point (float), double-precision floating-point type (double).

printf (), scanf (): Outputs and inputs, gets and outputs information that interacts with the user.

Common placeholders:%d (int),%f (float),%LF (double),%c (char),%s (string)

Accessor use method: scanf ("%d", &a);

Example:

Calculate Cylinder Volume

Float raduis,height,vol,pi=3.14;//declares two variables for saving radii and high

printf ("Please enter radius: \ n");

scanf ("%f", &raduis);

printf ("Please enter High: \ n");

scanf ("%f", &height);

vol = pi*raduis*raduis*height;

printf ("Volume vol=%0.2f of Cylinders", vol);

Example 2:

Print a small ticket for shopping

Float price=20,totalprice,realprice,discount;//toothpaste Price

Float total,change;//Payment Amount and change

int num;//The quantity of toothpaste to buy

printf ("The price of toothpaste is $20 per \ n");

printf ("Please enter the quantity of toothpaste purchased: \ n");

scanf ("%d", &num);//Gets the number of inputs

printf ("Please enter a discount: \ n");

scanf ("%f", &discount);//Get the discount you entered

printf ("Please enter payment amount: \ n");

scanf ("%f", &total);//Get Payment amount

Totalprice = price*num;//Calculated Total Price (original price)

Realprice = (1-discount) *totalprice;//calculates the amount due

Change = total-realprice;//Calculate change

printf ("*************** Shopping small ticket **************\n");

printf ("Unit price \ t number \ n");

printf ("%0.2f\t%d\t%0.2f\n", Price,num,totalprice);

printf ("Discount:%0.2f, discounted price:%0.2f\n", Discount,discount*totalprice);

printf ("Payable:%0.2f, paid:%0.2f, change:%0.2f\n", Realprice,total,change);

printf ("************************************");

Arithmetic operators: Divided into unary operators and two-tuple operators

Binary operator (operand two): +,-, *,/,% (for redundancy or modulo)

Unary operator (only 1 operands): + + (from + 1),--(auto minus 1)

Example:

int num=5;

printf ("%d\n", num++);//5

printf ("%d\n", num);//6

printf ("%d\n", ++num);//7

printf ("%d\n", num);//7

printf ("*************************\n");

printf ("%d\n", num--);//7

printf ("%d\n", num);//6

printf ("%d\n",--num);//5

printf ("%d\n", num);//5

Type conversions: auto-conversions and casts

Automatic conversion:

1. Two types of data are compatible with each other

2. The target type is larger than the source type---> range of small can be a large range of automatic conversion

Short--->int--->long--->float--->double

Cast: A loss of progress may occur during the casting process

Syntax: (data type) variable or numeric value;

Example:

int a=3,b=2;

float c,d,e,f;

c=a/b;//1.000000

D= (float) (A/b);//1.000000

E= (float) a/b;//1.500000

f= (int) c%a;//1.000000

Example: Swapping two numeric values for an input

1. Get the two values entered by the user and complete the interchange

int num1,num2,temp;

printf ("Please enter the value of NUM1: \ n");

scanf ("%d", &num1);

printf ("Please enter the value of num2: \ n");

scanf ("%d", &num2);

printf ("Before Exchange: num1=%d,num2=%d\n", num1,num2);

Exchanging values for NUM1 and num2

TEMP=NUM1;

num1=num2;

Num2=temp;

printf ("After Exchange: num1=%d,num2=%d\n", num1,num2);

Example: Calculates the area of the trapezoid based on the value entered by the user

float top,bottom,height,s;

printf ("Please enter the bottom of the ladder: \ n");

scanf ("%f", &top);

printf ("Please enter the bottom of the ladder: \ n");

scanf ("%f", &bottom);

printf ("Please enter the trapezoid high: \ n");

scanf ("%f", &height);

S= (top+bottom) *height/2;//calculated area

printf ("trapezoidal area:%0.2f", s);

Set sail, C language basic content finishing