من طرف Introduction:
There are basically two types of languages used to program computers:
1. Low level languages: known as Assembly language, which is the symbolic representation of the actual machine instructions executed by the computer. Assembly language can be used to create to create very efficient programs, but it provides no built-in control structures or I/O functions. The programmer, so many people find that assembly language is a difficult task, must manually construct all such items.
2. High level languages: a high- level language supplies the programmer with various control structures, input and out put commands, and the likes, which make programming easier and faster. However, the elements of a high- level language may not relate directly to the way that the computer ultimately carries out the program. So high-level language is less efficient than the assembly language.
There is a need to balance between the eases of use and with efficiency. Many programmers feel that C provides this balance. It successfully combines the structure of a high-level language with the power and efficiency of assembly language. Since it spans the gab between assembly language and high-level languages, it is called a middle-level language.
A short History of C:
C was invented and first implemented by Dennis Ritchie, using the UNIX operating system. C is the result of a development process that started with an older language called BCPL. BCPL influenced a language called B that was invented by Ken Thompson and that led to the development of C in the 1970’s.
Understand the Component of A C Program:
All C programs share certain essential components and traits. All C programs consist of one or more functions, each of which contains one or more statements. In C, a function is a named subroutine that can be called by other parts of the program. Functions are the building blocks of C. A statement specifies the action to be performed by the program. In other words, statements are the parts of your program that actually perform operations.
The general form of a C function is:
ret-type function-name(param-list)
{
statement sequence
}
Here, ret-type specifies the type of data returned by the function; function-name is the name of the function. Information can be passed to the function through the parameters, which specified in the function’s parameter list, param-list. The statement sequence may be on or statements.
Note:
• All C statement ends with a semicolon (
.
• C does not recognise the end of the line.
Function name, control under some rules. Function name can be composed of any upper-lowercase letters, the digits 0-9, and the underscore.
Note:
• A digit cannot start a function name.
• C is case-sensitive, which means that C recognises the difference between upper-and lowercase letters, e.g. Myfun and myfun are entirely different names.
The function that every C program must have is main (). The main() function is where execution of your program begins. That is, when your program begins running, it starts executing statements inside main(), beginning with the statement after the opening curly brace. Your program ends when main()’s closing curly brace is reached.
Library Functions:
The ANSI (American National Standards Institute) C standard specifies a set of library functions to be supplied by all C compilers. This collection of functions is usually referred to as C standard library. The standard library contains functions to perform disk I/O, string manipulation, mathematical computation, and much more. When your program is compiled, the code of each library function used by the program is automatically included. Library function can be enhanced and extended as needed to accommodate changing circumstances. E.g. printf() is one of the library function that allow to print some thing to the screen.
• Note that the library function is a statement must end with a semicolon.
Header files:
Another common component in most C programs, the header files, is where the information of library functions is found. These files all end with .H extension. The C compiler used the information in these files to handle the library functions properly. To add these files to your program you use #include pre-processor directive. The #include directive tell the pre-processor to read in another file and include it with your program.
The most commonly required header file is called STDIO.H. Here is the directive that includes these files: #include <stdio.h>
Example:
#include <stdio.h>
int main(void)
{
printf (“This is my first program.”);
return 0; }
There are basically two types of languages used to program computers:
1. Low level languages: known as Assembly language, which is the symbolic representation of the actual machine instructions executed by the computer. Assembly language can be used to create to create very efficient programs, but it provides no built-in control structures or I/O functions. The programmer, so many people find that assembly language is a difficult task, must manually construct all such items.
2. High level languages: a high- level language supplies the programmer with various control structures, input and out put commands, and the likes, which make programming easier and faster. However, the elements of a high- level language may not relate directly to the way that the computer ultimately carries out the program. So high-level language is less efficient than the assembly language.
There is a need to balance between the eases of use and with efficiency. Many programmers feel that C provides this balance. It successfully combines the structure of a high-level language with the power and efficiency of assembly language. Since it spans the gab between assembly language and high-level languages, it is called a middle-level language.
A short History of C:
C was invented and first implemented by Dennis Ritchie, using the UNIX operating system. C is the result of a development process that started with an older language called BCPL. BCPL influenced a language called B that was invented by Ken Thompson and that led to the development of C in the 1970’s.
Understand the Component of A C Program:
All C programs share certain essential components and traits. All C programs consist of one or more functions, each of which contains one or more statements. In C, a function is a named subroutine that can be called by other parts of the program. Functions are the building blocks of C. A statement specifies the action to be performed by the program. In other words, statements are the parts of your program that actually perform operations.
The general form of a C function is:
ret-type function-name(param-list)
{
statement sequence
}
Here, ret-type specifies the type of data returned by the function; function-name is the name of the function. Information can be passed to the function through the parameters, which specified in the function’s parameter list, param-list. The statement sequence may be on or statements.
Note:
• All C statement ends with a semicolon (
.• C does not recognise the end of the line.
Function name, control under some rules. Function name can be composed of any upper-lowercase letters, the digits 0-9, and the underscore.
Note:
• A digit cannot start a function name.
• C is case-sensitive, which means that C recognises the difference between upper-and lowercase letters, e.g. Myfun and myfun are entirely different names.
The function that every C program must have is main (). The main() function is where execution of your program begins. That is, when your program begins running, it starts executing statements inside main(), beginning with the statement after the opening curly brace. Your program ends when main()’s closing curly brace is reached.
Library Functions:
The ANSI (American National Standards Institute) C standard specifies a set of library functions to be supplied by all C compilers. This collection of functions is usually referred to as C standard library. The standard library contains functions to perform disk I/O, string manipulation, mathematical computation, and much more. When your program is compiled, the code of each library function used by the program is automatically included. Library function can be enhanced and extended as needed to accommodate changing circumstances. E.g. printf() is one of the library function that allow to print some thing to the screen.
• Note that the library function is a statement must end with a semicolon.
Header files:
Another common component in most C programs, the header files, is where the information of library functions is found. These files all end with .H extension. The C compiler used the information in these files to handle the library functions properly. To add these files to your program you use #include pre-processor directive. The #include directive tell the pre-processor to read in another file and include it with your program.
The most commonly required header file is called STDIO.H. Here is the directive that includes these files: #include <stdio.h>
Example:
#include <stdio.h>
int main(void)
{
printf (“This is my first program.”);
return 0; }
