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− | {{ | + | {{C Guide}} |
− | + | Many programs are far more complex than just printing a sentence or two on the screen. To be able to perform more complex operations and calculations we need a way to store values temporarily during the program execution. These named stored locations are called '''variables'''. | |
== Data Types == | == Data Types == | ||
− | {{main| | + | {{main|Data types - C|l1=Data Types}} |
− | + | In [[C]], every variable must have a type which specifies what kind of data it could hold. The type of variable determines how the variable is stored and what operations can be performed on it. For example, a variable of type int can store integers such as 2, -9, 83, and 5294. By contrast with float, which is capable of storing floating point values such as 3.4, 30, -943.234, and 2e6. C provides a wide variety of types in addition to an int and a float, including: char, short, and double. | |
=== Minimum Magnitudes === | === Minimum Magnitudes === | ||
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For example, the following are valid variable names: | For example, the following are valid variable names: | ||
− | + | x foo | |
− | + | x_y_z BaR | |
− | + | _foo bar45 | |
− | + | _1 baz | |
− | + | thisIsAReallyLongVariableName | |
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The following, however, are not valid variable names: | The following, however, are not valid variable names: | ||
− | + | 2 $apples | |
− | + | 5foo double | |
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== Variable Declaration == | == Variable Declaration == | ||
A '''variable declaration''' is a statement that announces to the translator the creation of a new object and the kind of properties it possess. These properties include: | A '''variable declaration''' is a statement that announces to the translator the creation of a new object and the kind of properties it possess. These properties include: | ||
− | * The | + | * The [[storage class - C|object's lifetime]] |
− | * The object's | + | * The object's [[data types - C|data type]] |
− | * Whether an object is | + | * Whether an object is [[volatile - C|volatile]] |
− | * Whether it's a | + | * Whether it's a [[restricted pointers - C|restricted pointer]] |
− | * Whether it's an | + | * Whether it's an [[atomic variables - C|atomic variable]] |
− | * Whether an object is | + | * Whether an object is [[const - C|modifiable]] |
These properties are collectively named ''declaration-specifiers''. | These properties are collectively named ''declaration-specifiers''. | ||
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<source lang="C"> | <source lang="C"> | ||
int foo = 1, bar = 2, baz = 3; | int foo = 1, bar = 2, baz = 3; | ||
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</source> | </source> | ||
[[Category:C programming language]] | [[Category:C programming language]] | ||
[[Category:C variables]] | [[Category:C variables]] |