Scope of variables
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This document discusses variables in C programming. It defines variables as placeholders like in algebra that can store and represent data. It explains that variable names in C can include letters, digits and underscores, but must begin with a letter. The document also distinguishes between local and global variables, with local variables only being accessible within the function they are declared in, while global variables can be accessed throughout a program after their declaration outside of any function.
Scope of variables
- 3. Disclaimer: This presentation is prepared by trainees of baabtra.com as a part of mentoring program. This is not official document of baabtra.com – Mentoring Partner
- 4. What are Variables in C Variables in C have the same meaning as variables in algebra Eg: x = a + b z + 2 = 3(y - 5) variables in algebra are represented by a single alphabetic character.
- 5. Variable names in c 1. May only consist of letters, digits, and underscores 2. May be as long as you like, but only the first 31 characters are significant 3. May not begin with a number
- 6. Naming Conventions Begin variable names with lowercase letters Use meaningful identifiers Separate “words” within identifiers with underscores or mixed upper and lower case. Eg: int int_a; char str_a;
- 7. There are two places where variables can be declared in C programming language: 1. Inside a function or a block which is called “local variables” 2. Outside of all functions which is called “global variables”.
- 8. Local Variable Variables that are declared inside a function are called local variables. They can be used only by statements that are inside that function . Local variables are not known to functions outside their own.
- 9. Eg:#include <stdio.h> Void main () { /* local variable declaration */ int int_ x, int_ y; Int int_ c; /* actual initialization */ int_ x = 5; int_y = 20; int_ c = int_x + int_ y; printf ("value of x = %d, b = %d and c= %dn", int_x, int_y, int_ c); }
- 10. Global variables are defined outside of a function, usually on top of the program. The global variables will hold their value through out the lifetime of your program and they can be accessed inside any of the functions defined for the program. A global variable can be accessed by any function. That is, a global variable is available for use through out your entire program after its declaration. Global Variables
- 11. Eg: #include <stdio.h> /* global variable declaration */ int int_ g; Int main () { /* local variable declaration */ int int_ a, int_b; /* actual initialization */ int_ a = 10; int_ b = 20; int_ g = int_ a + int_ b; printf ("value of a = %d, b = %d and g = %dn", int_ a, int_ b, int_ g); return 0;
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