C Language cheat sheet

# C Language cheat sheet **aim:** > 1. to add some value in our *resume* and show Teamwork our Skills to recruiter. > 2. this blog will help many first year students + learners > 3. this blog will uploaded on DEV.to So more people will interact > 4. this blog will help us to revise C in less time > 5. any of our team member can use this blog and this markdown but (fair credits should be given) plese find this [Link](https://github.com/adam-p/markdown-here/wiki/Markdown-Cheatsheet) or copy paste this url directly in your browser. **https://github.com/adam-p/markdown-here/wiki/Markdown-Cheatsheet** **please find this [Resource](https://kupdf.net/downloadFile/5985fac3dc0d609a11300d19) and TRY TO USE it!!! or write your OWN words.** # TOC + MAP > **Some words+motivation for Biginers Goes here!+** > **PDF Link to download(Putting first so pps can Download it)** # Hunaid Nakhuda <a name="hunaid-1"></a> # Introduction ## **Environment Setup** To set up your environment for C programming language, you need the following two software tools available on your computer, (a) Text Editor (b) The C Compiler. - [ ] Environment Setup - [ ] Program Structure # Variable:- variable names may consist of letters,digits,and the underscore(_) some rules to define variables:- 1.They must begin with a letter. Some system permit underscore as the first character. 2.ANSI standard recognizes a length of 3 charecters.However, length should not be normally more than eight characters. 3.Variable names are case sensitive. 4.It should not be a keyword. 5.White space is not allowed - [ ] Constant - [ ] Keywords - [ ] Data type - [ ] Printf ScanF - [ ] Operator # Dinky Lakhani - [ ] **If else**  There are numerous conditions that can be used to compare two variables and execute a certain piece of code based on the condition satisfied . Following are few conditions : | Particulars | Operators | | ------------- |:-------------:| | Equals | == | | Not Equal | != | | Greater than | a > b | | Less than | a = b | | Less than or equal to | a <= b | These conditions can be used in several ways . One of which is using ```If-else``` statements. **If statement:** ``` int main() { int a = 5; int b = 20; if (b > a) printf("b is greater than a"); return 0; } ``` In the above code , if b is greater than a will be true and the output will be : ```b is greater than a``` **If - else if statement:** ``` int main() { int a = 5; int b = 5; if (b > a) printf("b is greater than a"); else if(a==b) printf("a is equal to b"); return 0; } ``` In the above example , the first condition turns out to be false and the control reaches to **```else if ```** statement . Thus , the output is ```a is equal to b``` **If - else statement:** ``` int main() { int a = 5; int b = 3; if (b > a) printf("b is greater than a"); else if(a==b) printf("a is equal to b"); else printf("a is greater than b"); return 0; } ``` In the above example , the first and the second condition turns out to be false and the control reaches to **```else```** statement . Thus , the output is ```a is greater than b``` - [ ] **Nested if**  If there is an ```if``` statement inside another **if** statement , it is known as nested if statement. **Nested If - else statement:** ``` int main() { int a = 5; int b = 3; int c = 10; if (a > b) { if(a>c) printf("Maximum is a = %d",a); else printf("Maximum is c = %d",c); } else { if(b>c) printf("Maximum is b = %d",b); else printf("Maximum is c = %d",c); } return 0; } ``` The output of the above code is : ``` Maximum is c = 10``` The first if condition is true so the control moves inside it and the nested if condition becomes false so the else condition is executed. - [ ] **Switch**  The switch statement is used to select one of the many blocks to be executed. ``` int main() { int month = 5; switch (month) { case 1: printf("January"); break; case 2: printf("February"); break; case 3: printf("March"); break; case 4: printf("April"); break; case 5: printf("May"); break; case 6: printf("June"); break; case 7: printf("July"); break; case 8: printf("August"); break; case 9: printf("September"); break; case 10: printf("October"); break; case 11: printf("November"); break; case 12: printf("December"); break; default: printf("Error"); exit(1); } } ``` The output of the above code is **```May```** In the above code , the switch statement evaluates the expression passed into its corresponding parenthesis. The output of the evaluation is used by the case . If there is a match in the case statements , the code following it is executed and the break keyword helps in exit from the switch statement. Whereas, the default statement is executed if no match is found . **NOTE ``` Default statement must always be placed at the end of the switch statement.```** - [ ] **For loop**  When we know how many times a particular piece of code is to be repeatedly executed, the for loop is used. Its syntax is as follows : ``` for(expression 1 ; expression 2 ; expression 3) { //code to be repeatedly executed } ``` *expression 1* is called the initialization statement to set the beginning offset of the loop *expression 2* is called the test condition statement to check for the continuation of the loop . It is also known as the **exit condition**. *expression 3* is the statement that gets executed every time after the loop gets executed . It is usually an increment or decrement statement. For e.g. : ``` int main() { int i ; for(i=0;i<10;i++) { printf("%d",i); } return 0; } ``` The output of the above code is : **```0123456789```** The iterator i is initialised with 0 and the test condition is checked . 0 is printed and the value of i gets incremented . Now , the value is i=1 . As it is less than 10 , the printf statement gets executed. This process keeps on repeating until the value of i becomes 10. Since , 10 is not less than 10 , the loop stops. **Infinite Loop** If a user forgets to either increment/decrement the iterator or it forgets the exit condition , the loop gets repeated for an infinite number of times . This is an error and may sometimes crash the system. E.g. : ``` for(;;) { printf("hello world! "); } ``` Observe the loop carefully . None of the conditions are mentioned and thus it will print hello world! for infinite time period till user explicitly stops the execution. - [ ] **While loop**  When we are not aware of the number of times the loop is to be repeated , the while loop is used. While loop gets executed as long as the condition is true . **Remember** to initialize the iterator at the beginning of the while loop and to increment/decrement the iterator (for exitting the loop) inside the while loop (preferrably at the end of while loop). The syntax for the same is illustrated with an example as follows : ``` int main() { int i = 0 ; //initializing iterator while(i<10) //test condition { printf("%d",i); i++; //increment statement } return 0; } ``` The output of the above code is : **```0123456789```** **Infinite Loop** If the condition is always true rather it never becomes **false**, the loop gets repeated for an infinite number of times . This is an error and may sometimes crash the system. E.g. : ``` char ch = 'a'; while(1) { printf("%c",ch); } ``` The condition following the while is always true i.e while it is 1 and thus it will print aaa.... infinite times till user explicitly stops the execution. - [ ] **Do while**  The do while is similar to while except that it gets executed atleast once before checking the condition and the loop is repeated as long as the condition is true. **Note** the semicolon at the end of the loop The syntax of the loop is illustrated with an example as follows: ``` int main() { int i = -1 ; //initializing iterator do { i++; //increment statement printf("%d",i); }while(i<0); //Test condition return 0; } ``` The output of the above piece of code will be : **```0```** - [ ] **Nested loop**  Sometimes called as **"Loop inside Loop"**. There can be any combination such as for loop inside another for loop , while inside while , do while inside another do while . There can also be hybrid nested loops i.e. while inside for and similar combinations . For e.g. : ``` int main() { for(int i=0;i<3;i++) { for(int j=0;j<3;j++) { printf("%d ",i*j); } printf("\n"); } return 0; } ``` The output will be : ``` 0 0 0 0 1 2 0 2 4 ``` ## Vivek Patel ## Array - An array is fixed-size sequenced collection of elements of same data type. - it is data structure that can stores a fixed-size sequential elements of same Data type. **Types of arrays** 1. One-dimentional arrays 2. Two-dimentional arrays 3. Multi-dimentional arrays //photo array variable and index One Dimentional arrays //Photo 1d arrays define : datatype array_name[size]; It must be a valid identifier and should follow veriable declaration rules ``` int a[99]; float point[20]; char name[50]; ``` * num is an array of type int, which can only store 99 elements of type int. * x is an array of type float, which can only store 20 elements of type float. * name is an array of type char, which can only store 50 elements of type char. - [ ] md array - [ ] typedef and #define - [ ] Function - [ ] String functions - [ ] Math functions ## SoumyaDeep Ghosh - [ ] Structure - [ ] Union - [ ] Enum - [ ] File handling - [ ] Graphics - [ ] Malloc and calloc again pdf, Credits here ,,Thanks,Final Words from team. Resources Used in blog : https://www.amazon.in/dp/B076Y39SHL/ref=cm_sw_em_r_mt_dp_502V7XH78C52KBEDGSV3?_encoding=UTF8&psc=1

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