C language learning log 10.4

One . Loop statement

if Statement can determine whether the condition is satisfied , When you are satisfied, do the corresponding action , The loop statement can be used when the condition is satisfied , Keep repeating some actions .

Repeated statements （ Loop statement ） You can execute other statements multiple times , It checks whether a logical condition is satisfied , Execute its loop body only when it is satisfied .

while A statement is a loop statement , It will first determine whether a condition is satisfied , If the conditions are met , Execute the statement or statement parentheses that follow , Then judge again whether the conditions are met , If the conditions are met, execute again , Until the conditions are not met . The statement or statement parentheses that follow , It's a circular body .

do-while Circulation and while The loop is very similar , The only difference is that we only judge the condition at the end of the loop body execution . in other words , in any case , The loop is executed at least once , And then judge the conditions . And while The same thing about the cycle is , Execute the loop when the conditions are met , End the cycle when the condition is not satisfied .

Two . Measuring digit （ Greater than or equal to 0 Number of numbers ）

#include<stdio.h>
int main(void)
{ int n=0;  int a;
  scanf("%d",&a);
  n++;
  a/=10;
  while(a>0){
  	n++;
  	a/=10;}
  	printf("%d",n);
}

Tip: Several boundary numbers commonly used in testing programs ：“ Single digit ;10;0; negative ”