Introduction to c programming
- 2. Program is a collection of instructions that will perform some task. Source code of a Hello World program written in the C programming language #include <stdio.h> int main(void) { printf("Hello world!n"); return 0; }
- 3. C was developed by Dennis Ritchie at Bell laboratory in 1972 It is an upgraded version of languages B and BCPL.
- 4. It is a structured programming language. It is highly portable. It is a middle level language. It is a case sensitive language. It uses Top-Down approach. It is a Free form language.etc,.
- 5. GLOBAL DECLARATION SECTION DOCUMENTATION SECTION PREPROCESSOR SECTION DEFINITION SECTION main() { Declaration part; Executable Part; } sub program section { Body of the subprogram; }
- 6. Enter the program in a C editor. Save the program (File Save) or F2. Use the extension .c for saving the file. Eg: sample.c Compile the program(Compile Compile) or Alt+F9. Run the program(Run Run) or Ctrl+F9.
- 7. Enter the program in vi editor. Save the file using :wq Use the extension .c for saving the file. Eg: sample.c Compile the program. Eg: cc sample.c (or) gcc sample.c Run the program using a.out.
- 8. Identifiers are names given to various program elements such as functions and arrays etc,. › Example: int total,marks; › Here total and marks are user defined identifiers.
- 9. First character must be alphabetic or underscore. Must consist only of alphabetic characters, digits, or underscores. Only the first 31 characters of an identifier are significant and are recognized by the compiler. Cannot use a keywords or reserved word (e.g. main, include, printf & scanf etc.). No space are allowed between the identifiers etc,. C is case sensitive, e.g. My_name my_name.
- 10. Valid Names Invalid Names a a1 $sum /* $ is illegal */ student_name stdntNm 2names /* Starts with 2 */ _aSystemName _anthrSysNm stdnt Nmbr /* no spaces */ TRUE FALSE int /* reserved word */ Variables : Variable is an identifier that is used to represent some specified type of information. Eg: x=3 Here x is variable.
- 11. auto register continue double typedef for int char signed struct extern void break return default else union goto long const sizeof switch float do case short if enum unsigned static while It is a reserved word, which cannot be used for anything else. Examples:
- 12. Constants Character Constants Numeric Constants Real Constant Integer Constant String Constant Single Character Constant Constants Numeric Constants Integer Constant Constants Numeric Constants Real Constant Integer Constant Constants Numeric Constants Single Character Constant Real Constant Integer Constant Constants Numeric Constants String Constant Single Character Constant Real Constant Integer Constant Constants Numeric Constants Constants Numeric Constants Character Constants Numeric Constants It is an entity whose value does not changes during the execution.
- 13. Integer constants It is formed using a sequence of digits. Decimal - 0 to 9 . Octal - 0 to 7. Hexa - 0 to 9 ,A to F Eg: 10,75 etc. Rules for defining Integer Constant: It must have at least one digit. Decimal point are not allowed. No blank space or commas are allowed. It can be either positive or negative. Etc,.
- 14. Real constants It is formed using a sequence of digits but it contain decimal point. length, height, price distance measured in real number. Eg: 2.5, 5.11, etc.
- 15. Single character constant A character constant is a single character they also represented with single digit or a single special symbol which is enclosed in single quotes. Eg: ‘a’, ‘8’,’_’etc. String constants String constant are sequence of characters enclosed with in double quote. Eg: “Hello” ,”444”,”a” etc,.
- 16. Data Types A data type is a classification identifying one of various types of data, such as real-valued, integer or Boolean, that determines the possible values for that type
- 17. A number without a fraction part : integral number. Integer occupies 2 Bytes. The Control or Format String for integer is %d. C supports three different sizes of the integer data type : short int int long int
- 18. A floating-point type is a number with a fractional part, e.g. 56.78. Floating point numbers occupies 4 Bytes. The Control or Format String for float is %f. C supports three different sizes of the float data type Double float long double
- 19. Character are generally stored using 8 bits(1 Byte) of the internal storage. The Control or Format String for Character is %c. Character ASCII code value a 97(decimal) or 01100001(binary) x 120(decimal) or 01111000(binary)
- 20. The void type has no values and no operations. Both the set of values and the set of operations are empty.
- 21. Data type Size(bytes) Range Format string (or)Control String Char 1 128 to 127 %c Unsigned char 1 0 to 255 %c Short or int 2 -32,768 to 32,767 %i or %d Unsigned int 2 0 to 65535 %u Long 4 -2147483648 to 2147483647 %ld Unsigned long 4 0 to 4294967295 %lu Float 4 3.4 e-38 to 3.4 e+38 %f or %g Double 8 1.7 e-308 to 1.7 e+308 %lf Long Double 10 3.4 e-4932 to 1.1 e+4932 %lf
- 22. To create a variable, you must specify the type. Example: float price; int a,b; char code;