PHP流程控制

PHP流程控制

 

PHP流程控制分为两种类型：

         判断结构：根据条件式的结果执行不同的动作

         循环结构：可以重复运行某段代码

判断结构：

         单向选择（if）：if(condition){

                                                         statement;

                                                  }

         双向选择(if…else…)：if(condition){

                                                         statement;

                                                  }else{

                                                         statement;

                                                  }

         多重选择(if…elseif…):if(condition）{

                                                         statement1;

                                                  }

                                                  elseif(condition2) {

                                                         statement2;

                                                  }

                                                   …

                                                 else{

                                                         statement;

                                                 }

         判断选择(switch):switch(experession){

                                                        case value1:

                                                                           Statement1;

                                                                           break;

                                                        …

                                                        default:

                                                                          StatementＮ;

　　　　　　　　　　　　　　}

循环结构：

         计数循环(for)：for(initializers;expersions;iterators){

                                                    statements;

                                    }

         条件式循环(while)：while(condition){

                                                     statements;

                                    }

         先执行后判断(do…while):do{

                                                     statements;

                                    }while(condition);

 

         Break与continue:break用来强制离开循环，continue用于结束本次循环，开始下次循环

         Exit()与die():exit与die可以强制退出程序。在括号里面可以加参数以在网页上显示字符串。                                                       

数组循环(foreach)：

　　foreach(arrary_name as $value){

                        statement;

        }

　　foreach(arrary_name as $key=>$value){

                        statements;

         }