2015-12-03ios Class Summary

I. ①int age = 20

As on the INT naming convention, int (uppercase and lowercase characters, numbers, underscores ) = ()/The contents of parentheses must start with a letter

When there are multiple words in a variable name, the first word is lowercase, the second word is capitalized (the next word is capitalized), such as Numberofpeople, and is also known as the name.

②SCANF: receiving input from the terminal must be in strict accordance with the scanf format scanf ("" ",& parameter); The parameter must be the address of the variable,,& represents the fetch address. do not add spaces between quotation marks in an easy area

Get Char: Receives one character at a time from a terminal

int operation

scanf ("",& operation), where the operation is declared variable, declares a variable (the system does not immediately allocate memory space ) and defines a variable ( allocating memory space immediately, saving the value ) has a difference

Two. Basic operators

Priority of type: short--int--float--double, from low to high.

Example: int integer converted to floating point type

① cast: Int (float) result= (float+) noun/noun;

② Stealth Conversion: Int (float) result= noun (*0.1)/noun;

a++ (Delay +1, when the statement is completed first and then add 1)

++a (immediately +1, add 1 before the statement operation): +-* Same as the arithmetic method

1?? int temp = 10

int re = (temp++) + 20

Re = 30;

2?? int re = temp + 20

ren=30;

temp = temp + 1;

Three. Conditional control statements

① Boolean value Bool:true false

Example: #include <stdbool.h>

BOOL isOK =false

②IF Conditional statement Nonzero is true, if it's 0, that's false.

if (expression) {

What will be done after the establishment

}

If Else

if (expression) {

What will be done after the establishment

}else{

Other things that are not going to be done in this situation

}

③switch statements

switch (an expression or a variable) {

The case must be a constant here:

printf ();

Break ,/If not added, the case will always be judged, and once a break is encountered, it jumps out immediately. Break is the function of jumping out of the current loop and jumping out of the switch.

Case ******:

........

Default

printf ("Unreasonable and illegal input");

16 in the binary is greater than 10: a means that 10,b means that 11,c means that the 12,d means that the 13,e means that the 14,f represents a 15 lift for example: 30 is represented as: 1E

④for Loop Statements

while (conditional statement) {

It will be done when the condition is fulfilled, and the condition will be circulated.

}

Do .... While statement

Example: Calculating 1+2+ ... Value of 100

int total =0

bo=

Total + = i;//total=total+i

i++;

}while (i<=100);

Do ... while and while are different: do ... while satisfies at least one time to execute, and while if not satisfied does not perform the following

Use the For Loop statement to calculate when 1+2+3+ ... 100 The sum of the time

1??

#include <stdio.h>

int main (viod) {

int temp = 0;

for (int i= 1; I <=100; i++) {

temp + = i;

}

printf ("%d", temp);

}

2??

#include <stdio.h>

int main (viod) {

int i = 0;

int temp = 0;

for (; I <=100; i++) {

temp + = i;

}

printf ("%d", temp);

}

I was defined earlier and can be omitted in the For statement.

3??

#include <stdio.h>

int main (viod) {

int i = 0;

int temp = 0;

for (; I <=100;) {

temp + = i;

i + +;

}

printf ("%d", temp);

}

i++ in the back, the results are constant.

The difference between break and continue: Break is to jump out of the loop, while continue is the end of the loop, directly to the next.

2015-12-03ios Class Summary