C Language Advanced--loop statement 07

The basic way to work with circular statements:

• Determine whether a loop body is executed by a conditional expression
• Conditional expressions Follow the principle of an if statement expression

The difference between do,while,for:

• Do statements are executed and then judged, and the loop body executes at least once
• While statements are first judged and executed, the loop body may not execute
• The For statement is first judged and then executed, which is more concise than the while

Do.....while the way the statement is looped:

 Do {    //loop}while (condition)

The loop mode of the while statement:

 while (condition) {    //Loop}

How to loop for the For statement:

 for (initialize; condition; Change the value of a condition) {     //loop  }

program Example 1:

#include <stdio.h>intF1 (intN) {    intRET =0; if(N >0 )    {         Do{ret+=N; N--; }         while(N >0 ); }        returnret;}intF2 (intN) {    intRET =0;  while(N >0) {ret+=N; N--; }        returnret;}intF3 (intN) {    intRET =0; inti =0;  for(i=1; i<=n; i++) {ret+=i; }        returnret;}intMain () {printf ("%d\n", F1 ( -)); printf ("%d\n", F2 ( -)); printf ("%d\n", F3 ( -)); return 0;}

This code is very concise, you can look a little bit, as a review

The difference between break and continue:

• Break indicates the execution of the entire loop is terminated
• Continue means terminating this cycle into the next cycle

In the loop you can use continue and break two statements, Lenovo to switch, inside each case must have a break statement, then we can use the Continue statement inside? The answer is no, the compilation will be an error.

program Example 2:

#include <stdio.h>voidF1 (intN) {    inti =0;  for(i=1; i<=n; i++)    {        if((i%2) ==0 )        {             Break; } printf ("%d", i); } printf ("\ n");}voidF2 (intN) {    inti =0;  for(i=1; i<=n; i++)    {        if((i%2) ==0 )        {            Continue; } printf ("%d", i); } printf ("\ n");}intMain () {F1 (Ten); F2 (Ten); return 0;}

This code is also very concise, you can see the right as a review

program Example 3:

1#include <stdio.h>2#include <malloc.h>3 4 intFuncintN)5 {6     inti =0;7     intRET =0;8     int* p = (int*)malloc(sizeof(int) *n);9     Ten      Do One     { A         if(NULL = = p) Break; -          -         if(N <5) Break; the  -         if(N > -) Break; -          -          for(i=0; i<n; i++) +         { -P[i] =i; +printf"%d\n", P[i]); A         } at          -RET =1; -} while(0 ); -      -printf"Free (p) \ n"); -      in      Free(p); -      to     returnret; + } -  the intMain () * { $     if(Func (Ten) )Panax Notoginseng     { -printf"ok\n"); the     } +     Else A     { theprintf"error\n"); +     } -  $     return 0; $}

With 29 lines of code I can extend it to free a null pointer. Another wild pointer, the null pointer is by the difference, for this concept I will write another blog to supplement, after all, and this blog theme does not match, hehe.

Summary:

• The For loop is first judged after entering the loop body
• The For loop is suitable for occasions where the number of loops is fixed
• The while loop is first judged in the loop to enter the body execution
• The while loop is suitable for situations where the cycle times are variable
• The Do....while loop first executes the loop body and then the condition is judged
• Do.....while cycle at least once loop body

C Language Advanced--loop statement 07