假设学生的成绩范围在0到100分，规定90-100为A级，80-89为B级，70-79为C级，60-69为D级，0-59为E级，请编写程序输出结果。（先判断成绩是否为有效值，再判断等级）?

Answer 1

Assume that the student's score ranges from 0 to 100. It is specified that 90-100 is level A, 80-89 is level B, 70-79 is level C, 60-69 is level D, and 0-59 is level E. Please write a program to output the results. (First determine whether the score is a valid value, and then determine the grade)? - PHP Chinese website Q&A - Assume that the student's score ranges from 0 to 100 points. It is stipulated that 90-100 is A grade, 80-89 is B grade, and 70-79 is Level C, 60-69 is level D, 0-59 is level E. Please write a program to output the results. (First determine whether the score is a valid value, and then determine the level)? - PHP Chinese website Q&A

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Answer 2

仅供参考

if($grades>=0 and $grades<=100){
        switch($grades){
                case $grades<=100 and $grades >=90 :
                echo "成绩等级为A";
                break;
        
                case $grades<90 and $grades >=80 :
                echo "成绩等级为B";
                break;
                
                case $grades<80 and $grades >=70 :
                echo "成绩等级为C";
                break;
                
                case $grades<70 and $grades >=60 :
                echo "成绩等级为D";
                break;
        
                default :
                echo "成绩为E"；
}
}else{
        echo "成绩无效";
}