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7.1 Simple Assignment

A simple assignment expression computes the value of the right operand and stores it into the lvalue on the left. Here is a simple assignment expression that stores 5 in i:

i = 5

We say that this is an assignment to the variable i and that it assigns i the value 5. It has no semicolon because it is an expression (so it has a value). Adding a semicolon at the end would make it a statement (see Expression Statement).

Here is another example of a simple assignment expression. Its operands are not simple, but the kind of assignment done here is simple assignment.

x[foo ()] = y + 6

A simple assignment with two different numeric data types converts the right operand value to the lvalue’s type, if possible. It can convert any numeric type to any other numeric type.

Simple assignment is also allowed on some non-numeric types: pointers (see Pointers), structures (see Structure Assignment), and unions (see Unions).

Warning: Assignment is not allowed on arrays because there are no array values in C; C variables can be arrays, but these arrays cannot be manipulated as wholes. See Limitations of C Arrays.

See Assignment Type Conversions, for the complete rules about data types used in assignments.