- Functions In C++ Programming Language
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- As always, a function is a module of code that takes information in (referring to that information with local symbolic names called parameters), does some computation, and (usually) returns a new piece of information based on the parameter information.
- All the functions used in the program. And it is generally declared outside the function: main It is the user defined function and every function has one main function from where actually program is started and it is encloses within the pair of curly braces. The main( ) function can be anywhere in the program but in general practice it is.
Functions In C++ Programming Language
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The function prints the details of the player and passes the control back to main function. In line 22, deductfees function is called with an argument of type struct player. The function decrements the fees of the player by 1000 using the statement.
A function is a group of statements that together perform a task. Every C program has at least one function, which is main(), and all the most trivial programs can define additional functions.
You can divide up your code into separate functions. How you divide up your code among different functions is up to you, but logically the division is such that each function performs a specific task.
A function declaration tells the compiler about a function's name, return type, and parameters. A function definition provides the actual body of the function.
The C standard library provides numerous built-in functions that your program can call. For example, strcat() to concatenate two strings, memcpy() to copy one memory location to another location, and many more functions.
A function can also be referred as a method or a sub-routine or a procedure, etc.
Defining a Function
The general form of a function definition in C programming language is as follows −
A function definition in C programming consists of a function header and a function body. Here are all the parts of a function −
Return Type − A function may return a value. The return_type is the data type of the value the function returns. Some functions perform the desired operations without returning a value. In this case, the return_type is the keyword void.
Function Name − This is the actual name of the function. The function name and the parameter list together constitute the function signature.
Parameters − A parameter is like a placeholder. When a function is invoked, you pass a value to the parameter. This value is referred to as actual parameter or argument. The parameter list refers to the type, order, and number of the parameters of a function. Parameters are optional; that is, a function may contain no parameters.
Function Body − The function body contains a collection of statements that define what the function does.
Example
Given below is the source code for a function called max(). This function takes two parameters num1 and num2 and returns the maximum value between the two −
Function Declarations
A function declaration tells the compiler about a function name and how to call the function. The actual body of the function can be defined separately.
A function declaration has the following parts −
For the above defined function max(), the function declaration is as follows −
Parameter names are not important in function declaration only their type is required, so the following is also a valid declaration −
Function declaration is required when you define a function in one source file and you call that function in another file. In such case, you should declare the function at the top of the file calling the function.
Calling a Function
While creating a C function, you give a definition of what the function has to do. To use a function, you will have to call that function to perform the defined task.
When a program calls a function, the program control is transferred to the called function. A called function performs a defined task and when its return statement is executed or when its function-ending closing brace is reached, it returns the program control back to the main program.
To call a function, you simply need to pass the required parameters along with the function name, and if the function returns a value, then you can store the returned value. For example −
We have kept max() along with main() and compiled the source code. While running the final executable, it would produce the following result −
Function Arguments
If a function is to use arguments, it must declare variables that accept the values of the arguments. These variables are called the formal parameters of the function.
Formal parameters behave like other local variables inside the function and are created upon entry into the function and destroyed upon exit.
Introduction To Functions In C Programming Ppt
While calling a function, there are two ways in which arguments can be passed to a function −
Sr.No. | Call Type & Description |
---|---|
1 | Call by value This method copies the actual value of an argument into the formal parameter of the function. In this case, changes made to the parameter inside the function have no effect on the argument. |
2 | Call by reference This method copies the address of an argument into the formal parameter. Inside the function, the address is used to access the actual argument used in the call. This means that changes made to the parameter affect the argument. |
By default, C uses call by value to pass arguments. In general, it means the code within a function cannot alter the arguments used to call the function.
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C printf and scanf functions:
- printf() and scanf() functions are inbuilt library functions in C programming language which are available in C library by default. These functions are declared and related macros are defined in “stdio.h” which is a header file in C language.
- We have to include “stdio.h” file as shown in below C program to make use of these printf() and scanf() library functions in C language.
- In C programming language, printf() function is used to print the (“character, string, float, integer, octal and hexadecimal values”) onto the output screen.
- We use printf() function with
%d
format specifier to display the value of an integer variable. - Similarly
%c
is used to display character,%f
for float variable,%s
for string variable,%lf
for double and%x
for hexadecimal variable. - To generate a newline,we use “n” in C printf() statement.
Note:
- C language is case sensitive. For example, printf() and scanf() are different from Printf() and Scanf(). All characters in printf() and scanf() functions must be in lower case.
2 4 6 8 10 12 14 16 | intmain() charch='A'; floatflt=10.234; doubledbl=20.123456; printf('String is %s n',str); printf('Integer value is %dn',no); printf('Octal value is %o n',no); return0; |
Character is A String is fresh2refresh.com Float value is 10.234000 Integer value is 150 Double value is 20.123456 Octal value is 226 Hexadecimal value is 96 |
You can see the output with the same data which are placed within the double quotes of printf statement in the program except
- %d got replaced by value of an integer variable (no),
- %c got replaced by value of a character variable (ch),
- %f got replaced by value of a float variable (flt),
- %lf got replaced by value of a double variable (dbl),
- %s got replaced by value of a string variable (str),
- %o got replaced by a octal value corresponding to integer variable (no),
- %x got replaced by a hexadecimal value corresponding to integer variable
- n got replaced by a newline.
- In C programming language, scanf() function is used to read character, string, numeric data from keyboard
- Consider below example program where user enters a character. This value is assigned to the variable “ch” and then displayed.
- Then, user enters a string and this value is assigned to the variable “str” and then displayed.
2 4 6 8 10 12 | intmain() charch; printf('Enter any character n'); printf('Entered character is %c n',ch); printf('Enter any string ( upto 100 character ) n'); printf('Entered string is %s n',str); |
Enter any character a Entered character is a Enter any string ( upto 100 character ) hai Entered string is hai |
- The format specifier %d is used in scanf() statement. So that, the value entered is received as an integer and %s for string.
- Ampersand is used before variable name “ch” in scanf() statement as &ch.
- It is just like in a pointer which is used to point to the variable. For more information about how pointer works, please click here.
- printf() is used to display the output and scanf() is used to read the inputs.
- printf() and scanf() functions are declared in “stdio.h” header file in C library.
- All syntax in C language including printf() and scanf() functions are case sensitive.