php中关于break与continue两者之间的用法区别

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一般说来，程序进入循环体后在下次循环判断之前执行循环体里的所有语句，break和continue语句可以终止循环或忽略某些循环。

break： 此语句导致程序终止包含它的循环，并进行程序的下一阶段（整个循环后面的语句），即，不是跳到下一个循环周期而是循环。如果break语句包含在嵌套循环里，它只跳出最里面的循环。

#include<stdio.h>
int main()
{
int res=0;
int i=0;
int n=0;
printf("test break and continue
");
for(i=0;i<6;i++)
{
printf("start...
");
if(i==3)
        {
        printf("break 
");
        break;
        printf("break after
");
        //printf("continue 
");
        //continue;
        //printf("continue after
");
        }


printf("now i = %d
",i);
}
printf("test over !!!
");
return 0;
}

$ gcc -o bc bc.c
$ ./bc
test break and continue
start...
now i = 0
start...
now i = 1
start...
now i = 2
start...
break 
test over !!!
$

嵌套循环（break）：

#include<stdio.h>
int main()
{
int res=0;
int i=0;
int n=0;
printf("test break and continue
");
for(i=0;i<6;i++)
{
printf("start...
");
for(n=0;n<6;n++)
{
if(n==3)
        {
        printf("break 
");
        break;
        //printf("continue 
");
        //continue;
        }
printf("now n= %d
",n);
}
if(i==3)
        {
        printf("break 
");
        break;
        printf("break after
");
        //printf("continue 
");
        //continue;
        //printf("continue after
");
        }


printf("now i = %d
",i);
}
printf("test over !!!
");
return 0;
}

$ gcc -o bc bc.c
$ ./bc
test break and continue
start...
now n= 0
now n= 1
now n= 2
break 
now i = 0
start...
now n= 0
now n= 1
now n= 2
break 
now i = 1
start...
now n= 0
now n= 1
now n= 2
break 
now i = 2
start...
now n= 0
now n= 1
now n= 2
break 
break 
test over !!!
$

continue:循环语句里有此语句时，程序运行到此语句时，不在执行循环体里continue后面的语句而是跳到下一个循环入口处执行下一个循环。如果continue语句包含在嵌套循环语句里，它只影响包含它的最里层的循环。

#include<stdio.h>

int main()
{
int res=0;
int i=0;
int n=0;
printf("test break and continue
");
for(i=0;i<6;i++)
{
printf("start...
");
if(i==3)
        {
        //printf("break 
");
        //break;
        //printf("break after
");
        printf("continue 
");
        continue;
        printf("continue after
");
        }

printf("now i = %d
",i);
}
printf("test over !!!
");
return 0;
}

$ gcc -o bc bc.c
$ ./bc
test break and continue
start...
now i = 0
start...
now i = 1
start...
now i = 2
start...
continue 
start...
now i = 4
start...
now i = 5
test over !!!
$

嵌套循环（continue）：

#include<stdio.h>

int main()
{
int res=0;
int i=0;
int n=0;
printf("test break and continue
");
for(i=0;i<6;i++)
{
printf("start...
");

for(n=0;n<6;n++)
{
if(n==3)
        {
        //printf("break 
");
        //break;
        printf("continue 
");
        continue;
        }
printf("now n= %d
",n);
}

if(i==3)
        {
        //printf("break 
");
        //break;
        //printf("break after
");
        printf("continue 
");
        continue;
        printf("continue after
");
        }

printf("now i = %d
",i);
}
printf("test over !!!
");
return 0;
}

$ gcc -o bc bc.c
$ ./bc
test break and continue
start...
now n= 0
now n= 1
now n= 2
continue 
now n= 4
now n= 5
now i = 0
start...
now n= 0
now n= 1
now n= 2
continue 
now n= 4
now n= 5
now i = 1
start...
now n= 0
now n= 1
now n= 2
continue 
now n= 4
now n= 5
now i = 2
start...
now n= 0
now n= 1
now n= 2
continue 
now n= 4
now n= 5
continue 
start...
now n= 0
now n= 1
now n= 2
continue 
now n= 4
now n= 5
now i = 4
start...
now n= 0
now n= 1
now n= 2
continue 
now n= 4
now n= 5
now i = 5
test over !!!
$

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