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Home / C Tutorials The C language Operator Precedence in C by Marshall Brain Thursday, May 27, 1999
Published with kind permission of DevCentral C contains many operators, and because of the way in which operator precedence works, the interactions between multiple operators can become confusing. x=5+3*6; X receives the value 23, not 48, because in C multiplication and division have higher precedence than addition and subtraction. char *a[10]; Is a a single pointer to an array of 10 characters, or is it an array of 10 pointers to character? Unless you know the precedence conventions in C, there is no way to find out. Similarly, in E.11 we saw that because of precedence statements such as *p.i = 10; do not work. Instead, the form (*p).i = 10; must be used to force correct precedence.
The following table from Kernigan and Richie shows the precedence
hierarchy in C. The top line has the highest precedence.
Using this table, you can see that char *a[10]; is an array of 10 pointers to character. You can also see why the parentheses are required if (*p).i is to be handled correctly. After some practice, you will memorize most of this table, but every now and again something will not work because you have been caught by a subtle precedence problem. |
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This Article Introduction A simple program Branching/looping Arrays C Details Functions Libraries/makefiles Text files Pointers Parameters Dynamic structures Pointers and arrays Strings Operator precedence The command line Binary files
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