Branch and loop (two) (zero-based learning C language)

Continue to interpret putchar, getchar (the ASCII code value of \n is 10)

spaces and carriage returns will not be automatically cleared, still




remember to put parentheses in the buffer , the priority is different,
this is a good way to only print 1- 9 (using continue) a way that requires input

2. for loop (while loop and do while loop can be transformed into for loop)
The initialization of for loop conditions will only be executed once
while loop requires special attention to the initialization of loop conditions and loop variables adjustment

and is recommended for loop, because for loop code readability relatively high

semicolon between expression and expression note;


for loop execution flow


break; the three cycles are the same


but requires special attention to the Continue
the Continue is End the loop.
Skip the code behind continue and go directly to the judgment part of the condition.
Note that




modifying the variable may cause an endless loop.
Note that the assignment is = judgment is ==

recommended: the front is a closed interval, and the back is an open interval. Enhanced code
according to the situation

readability

in front of a closed interval, followed by a closed interval

some of the for loop variants of

the three conditions for loop can be omitted,
but if the judge for a conditional loop is omitted, indicating the condition of constant judgment is true, the endless loop
is not recommended If


you omit

it, you can omit it. In this case, after the outer layer loops once, j=10, but j will not be reset to 0;

it is recommended not to omit it.


Judgement condition is 0, don’t enter the loop,
assign =, judge as ==
3. do while loop
characteristics: the loop must be executed at least once.
Note: after the while (judgment statement); no less



break is the same.

Note that
continue will jump directly After the code behind this cycle, come back to do and execute the code directly. The


loop knowledge points are summarized and the
exercise starts
. 1. Calculate the n-th power

of i 2. Calculate the factorial
idea of i : cumulative multiplication





brute force search


binary search (guess number game) The method: narrow the range and compare with the intermediate value) at
most search log2n times
must be a number that has been arranged in order.



Example:





strcmp (string 1, string 2)
string comparison function, is a library function, need the header file #include <string.h>
If string 1 is equal to string 2, then this function returns 0.
If string 1 has more characters than string 2, then this function returns a number greater than 0.
If string 1 has fewer characters than string 2. Character then this function returns a number less than 0