The real work in a shader is done by computing values and making decisions. In the same manner as C++, GLSL has a rich set of operators for constructing arithmetic operations for computing values and a standard set of logical constructs for controlling shader execution.
No text describing a language is complete without the mandatory table of operator precedence (see Table 2.6). The operators are ordered in decreasing precedence. In general, the types being operated on must be the same, and for vector and matrices, the operands must be of the same dimension. In the table, integer types include int and uint and vectors of them, floating-point types include float and double types and vectors and matrices of them, ...