C language final without failing (Part 1)

Preface

： Everyone, learn from the scum , How do you do ？ The exam is coming soon ,c Language has learned ？ Don't talk much , Since none of you can , We only talk about dry goods , If you think the blogger is good , Welcome to the article three times , Your encouragement is the biggest gain for bloggers ！： sprint 90 Recommend by column 《c Language from 0->1》 In the past, we didn't fail the series ：

python Don't go to school （ On ）python Don't go to school （ in ）python Don't go to school （ Next ）

Basic input and output

main Function templates

Due to limited time , Let's just talk about Know what it is , , Don't speak Know why , If you want to know more about it, you can go to the column above Main function template

#include<stdio.h>int main(){  return 0;}

This Templates You must remember ！！！ remember return 0 Don't lose it

Input and output

Due to time , We will only cover the most commonly used inputs and outputs （printf and scanf）, Where the dream begins ,

#include<stdio.h>int main(){  printf(" End of term c Language must pass ");  return 0;}

printf sentence ： Output statement , The above code is output on the display , End of term c Language must pass , What we should pay attention to here is to remember printf(" "); Format , One （） and ”“, And finally A semicolon

A few escape characters ：’\n’,’\t’…… Generally, it is enough to remember these two

#include<stdio.h>int main() {  printf(" Autumn mountain code people , handsome ！\n I didn't fail at the end of the term ！");  return 0;}

\n Line break ,\t Tabulation

Output several common data types

#include<stdio.h>int main(){  int a = 18;  printf("%d",a);  return 0;}

This piece of , We define integer variables a, Then the output . We want to remember What's important is a few “%d%f……”, Let's just draw a conclusion , Now look at this picture ：

Focus on remembering , Byte length is OK ,char,int,double,float, Corresponding % Number is , %c,%d,%lf,%f

Input scanf

#include<stdio.h>int main() {  printf(" Please enter your age ");  int age;  scanf("%d", &age);  printf(" What is your age %d", age);  return 0;}

Look at the picture , It's not hard to find out ,scanf The syntax rule for is ：

scanf("% what ",& Variable );

Be careful ： & Be sure to remember ,” “ Is a variable type

printf in What is your age %d, Among them %d By age Instead of the output , Output ： What is your age 18

Basic operation rules +,-,*,/,%

This one has only ,/ and % Different from mathematics ,% It's surplus ,/ Yes, keep the whole

#include<stdio.h>int main() {  int a = 19;  int b = 3;  int c = a / b;  printf("%d", c);  return 0;}// Output ：6

#include<stdio.h>int main() {  int a = 19;  int b = 3;  int c = a % b;  printf("%d", c);  return 0;}// Output ：1

Examples of input and output

After the introduction above , I believe you are right to learn c Language has a basic concept , Let's look at it with examples ：

1. Input integer a,b, Output a+b
2. Output ’ a ‘,’ b ‘,’A‘ ,’ B’

#include<stdio.h>int main() {  int a, b;  scanf("%d%d", &a, &b);  printf("%d", a + b);  return 0;}

#include<stdio.h>int main() {  char a = 'a';  printf("%c %d\n",a,a);  char b = 'b';  printf("%c %d\n", b, b);  char A = 'A';  printf("%c %d\n", A, A);  char B = 'B';  printf("%c %d\n", B, B);  return 0;}

Remember these numbers, too , And so on ,a：97,A：65

Array

Define a length of 5 Of int Type of the array , Input , And output

int a[5[;a[0] = 1;a[1] = 2;a[2] = 3;a[3] = 4;a[4] = 5;

Many computers are made from 0 At the beginning , The first element of the array , Subscript to be 0

Select statement

Common logical operators

if

#include <stdio.h>int main(){  int a;  scanf("%d", &a);  if (a > 1)    printf("a Greater than 1");  return 0;}

if…else…

Implementation of conditions if What's in the sentence , Otherwise execution else Later

#include <stdio.h>int main(){  int a;  scanf("%d", &a);  if (a >= 60)    printf(" pass ");  else    printf(" fail, ");  return 0;}

if…else if…else

It is not difficult to guess by comparing the above , If … And if … otherwise …

#include <stdio.h>int main(){  int a;  scanf_s("%d", &a);  if (a >= 60 && a <= 70)    printf(" pass ");  else if (a > 70 && a <= 80)    printf(" good ");  else if (a > 80)    printf(" good ");  else    printf(" fail, ");  return 0;}

expression 1？ expression 2： expression 3

It means when expression 1 When it's true , Execute expression 2, Otherwise, execute the expression 3

#include<stdio.h>int main() {  char ch;  scanf("%c",&ch);  ch = (ch >= 'A' && ch <= 'Z') ? (ch + 32) : ch;  printf("%c", ch);  return 0;}

switch sentence

swtich( expression )  {    // () Only integers are supported for data types in                  case  Constant 1 :                    Statement to execute ;                   break;                 case  Constant 2 :                    Statement to execute ;                   break;                 case  Constant 3 :                    Statement to execute ;                    break;                 default:                    Statement to execute ;                   break;}

Be careful ：default, When the above conditions are not met , perform default sentence

Example

1. Judgement of leap year
2. Determine whether the character is a capital letter , If lower case letters are converted to upper case , Otherwise direct output （ See the conditional expression code above ）

// Leap year #include<stdio.h>int main() {  int y;  scanf_s("%d", &y);  if ((y % 4 == 0 && y % 100 != 0) || y % 400 == 0) {    printf("%d It's a leap year ", y);  }  else {    printf("%d It's not a leap year ", y);  }  return 0;}