C1-Basic Concepts

//

Main.m

C1_ Basic Concepts

//

Created by Dllo on 15/6/30.

Copyright (c) 2015 Zhozhicheng. All rights reserved.

//

#import <Foundation/Foundation.h>

int main (int argc, const char * argv[]) {

int a=10; Define a variable A, which has a value of 10

int b=20;

Single-line Comment

/*

* Multi-line Comment

*/

Defining variables

First part: type modifier, int,char,float

Part II: Variable names

Part III: Setting an initial value (normative problem)

int a = 10;

float B = 3.14;

Only one character in a single quotation mark in a character type variable

char c = ' A ';

//

Naming conventions for variable names

1. Variable names consist of numbers, letters, underscores, numbers cannot begin

int d = 10;

2. Variable names can not be the same as system reserved words, system reserved words will generally have color changes

int int = 20;

3. Variable names cannot be the same, even if the type is different

int a = 20;

float a = 20.0;

4. See the meaning of the name

int studentage = 20;

Char stusex = ' W ';

float Stuscoreboyhello = 37.5;

Hump Naming method

int a = 10;

A = 100; Assigning values to a variable

The equals sign has the lowest priority, and the last assignment is performed

A = 10 * 20 + 10;

//

int B = 20;

A = b;

//

How to Exchange values for two integer variables

int a = 10;

int B = 20;

int a = ten, b=20;

Defines a temporary variable that is used for temporary storage

Temp temporary variable

int temp = 0;

temp = A;

B-A

A = b;

Temp-B

b = temp;

//

Use only A and B to achieve a two number worth of exchange

int a = ten, B = 20;

A = a + B;

b = a A;

A = a-B;

Expressions: There are constants, variables, and operators, and expressions generally have a result

3 + 5 5

int a = 10,b = 20;

A + = b;;;;;

A semicolon is the end flag for a statement, and the expression is a semicolon, which is the statement

Basic input and OUTPUT functions

printf ("hello\n world\n");

//

int a = ten, B = 20;

printf ("a =%d B =%d\n", b,a);

float f = 3.14;

printf ("%f\n", f);

Keep three digits after the decimal point

printf ("%.3f\n", f);

//

char c = ' W ';

printf ("%c\n", c);

int a = 10;

printf ("%d\n", ++a);

++a a first +1, then the result after using +1

a++ the value of a first, then a +1 operation on a

printf ("%d\n", a);

//

// %

printf ("percent");

printf ("\ \");

//

int a = 0;

Using Input functions

scanf ("%d", &a);

printf ("%d\n", a);

Enter two numbers, and then swap the values of the two numbers and print the exchanged values

int a = 0, b = 0;

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

printf ("%d%d\n", b,a);

Define two variables

Enter the content you want to swap in

Exchange process

Results after the output exchange

int a = 10,b = 20;

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

Do not add \ n after the input function%d, and will be offset by the manual carriage return

A = a + B;

A = a-B;

A = a-B;

printf ("a =%d,b =%d\n", b);

return 10;

}

C1-Basic Concepts