I. Introduction
In practice, the C language, for circulation compared to the while loop and do-while loop is more flexible. The following brief summary of several uses for loop system.
Second, the specific usage
The general form for loop:
for (initialize; test; update)
statement;
initialize - initialization; test - test; update - update.
1 - update expressions can be used down counter
Example: for (secs = 5; secs> 0; --secs) {.......}
2 - update expressions can make the counter at a faster rate increase
Example: for (secs = 0; secs <60; secs + = 13) {.......}
3 - can be used instead of the digital count characters
Example: for (ch = 'a'; ch <= 'z'; ch ++) {.......}
4 - In addition to testing iterations, you can also test other conditions
示例: for (dried = 1; * dry dry dry * <= 600; dry ++) {} .......
5 - can make incremental amount of geometric growth rather than arithmetic growth
Example: for (secs = 10.0; secs <60.0; secs * = 1.3) {.......}
6 - update expressions can use any valid expression
示例：for (x = 1; y <= 75; y = (++x * 5) + 50) {.......}
[For the inner loop may be different variables, but this style is not very encouraged. ]
7-- expression may omit one or more (but not semicolons shown), as long as the end of the cycle can comprise statements in the loop can be
Example: for (n = 3; ans <= 25;) {ans * = n; .......}
[If you omit the test expression test conditions it would have been determined to be true, that for loop will always execute it. ]
8 - initialize expression is not necessarily the initial value to a variable, you can use printf () function, etc.
示例：for (n = 1，printf ("The n is %d.\n", n); n <= 5 ; n++) {ans *= n; .......}
9 - loop behavior can be changed in the expression loop header
Example: for (n = 1; n <= 25; n + = delta) {.......}
Parameters delta value can be changed in the loop body. ]