英文:
problem with a menu driven program consisting of switch()
问题
Here is the translated code portion without any additional information:
#include <stdio.h>#include <stdlib.h>int main() {int choice, num, i, fact;while (1) {printf("\n1-factorial\n");printf("2-prime\n");printf("3.odd/even\n");printf("4-exit\n");printf("your choice?\n");scanf("%d", &choice);switch (choice) {case 1:printf("enter a number");scanf("%d", &num);fact = 1;for (i = 1; i <= num; i++) {fact = fact * i; // factorial of a number}printf("factorial value is %d\n", fact);break; // ends the loop herecase 2:printf("enter a number");scanf("%d", &num);for (i = 2; i < num; i++) {if (num % i == 0) {printf("the number is not a prime number\n");break;}if (i == num) {printf("the number is prime\n");break;}}case 3:printf("enter a number");scanf("%d", &num);if (num % 2 == 0) {printf("the number is even\n");} else {printf("the number is odd\n");break;}case 4:exit(0); // terminates program execution included in the <stdlib.h>//default:printf("the choice is invalid\a\n"); // \a means alarm}}return 0;}
If you have any specific questions about the code or need further assistance, please feel free to ask.
英文:
#include<stdio.h>#include<stdlib.h>int main(){int choice,num,i,fact;while(1){printf("\n 1-factorial\n");printf("\n2-prime\n");printf("\n3.odd/even\n");printf("\n4-exit\n");printf("your choice?\n");scanf("%d",&choice);switch(choice){case 1:printf("enter a number");scanf("%d",&num);fact=1;for(i=1;i<=num;i++){fact=fact*i;//factorial of a number//}printf("factorial value is %d\n",fact);break;//ends the loop here//case 2:printf("enter a number");scanf("%d",&num);for(i=2;i<num;i++){if(num%i==0){printf("the number is not a prime number\n");break;}if(i==num){printf("the number is prime\n");break;}}case 3:printf("enter a number");scanf("%d",&num);if(num%2==0){printf("the number is even\n");}else{printf("the number is odd\n");break;}case 4:exit(0);//terminates program execution included in the <stdlib.h>//default:printf("the choice is invalid\a\n");//\a means alarm//}}return 0;}
i m not sure about the while loop like i have tried for(;;) too but i dont think thats the issue when i input 1 the factorial part works fine
but when i press 2 or 3
it says - enter a number and when i enter one
it again prompts me to enter a number
and then breaks
what maybe the issue here
i tried changing some logics but that didn't help i,googled it and it said something about buffer of \n but i couldn't understand it
答案1
得分: 1
I didn't quite understand your request, but here's the translated code:
我没有完全理解你的问题，但我在你的代码中看到了一个语法错误。所有的 switch case 后都必须跟着一个 break 语句。在这里，你只有一个 break 语句，而且是在第一个 case 后面。尝试在 case 2、3、4 和 default 的代码块后面加上 *break;* 看看是否可以解决你的问题。尝试像这样做：#include <stdio.h>#include <stdlib.h>int main(){int choice, num, i, fact;while (1){printf("1-factorial\n");printf("\n2-prime\n");printf("\n3.odd/even\n");printf("\n4-exit\n");printf("your choice?\n");scanf("%d", &choice);switch (choice){case 1:printf("enter a number");scanf("%d", &num);fact = 1;for (i = 1; i <= num; i++){fact = fact * i; // 阶乘}printf("阶乘值是 %d\n", fact);break; // 在此结束循环case 2:printf("enter a number");scanf("%d", &num);for (i = 2; i < num; i++){if (num % i == 0){printf("这个数字不是质数\n");break;}if (i == num){printf("这个数字是质数\n");break;}}break;case 3:printf("enter a number");scanf("%d", &num);if (num % 2 == 0){printf("这个数字是偶数\n");}else{printf("这个数字是奇数\n");break;}break;case 4:exit(0); // 终止程序执行，需要包含在 <stdlib.h> 中break;default:printf("选择无效\a\n"); // \a 表示警告break;}}return 0;}还要注意，阶乘的情况在一定范围的整数后将无法正常工作，因为阶乘值会超过 int 类型的大小。
英文:
I didn't quite understand your question, but I see a syntax error in your code. All switch cases must be followed by a break statement. Here as you can see there's only 1 break statement, that's after the first case. Try putting break; after the block of codes of case 2,3,4 and default and see if that resolves your problem
Try something like this:
#include<stdio.h>#include<stdlib.h>int main(){int choice,num,i,fact;while(1){printf("1-factorial\n");printf("\n2-prime\n");printf("\n3.odd/even\n");printf("\n4-exit\n");printf("your choice?\n");scanf("%d",&choice);switch(choice){case 1:printf("enter a number");scanf("%d",&num);fact=1;for(i=1;i<=num;i++){fact=fact*i;//factorial of a number//}printf("factorial value is %d\n",fact);break;//ends the loop here//case 2:printf("enter a number");scanf("%d",&num);for(i=2;i<num;i++){if(num%i==0){printf("the number is not a prime number\n");break;}if(i==num){printf("the number is prime\n");break;}}break;case 3:printf("enter a number");scanf("%d",&num);if(num%2==0){printf("the number is even\n");}else{printf("the number is odd\n");break;}break;case 4:exit(0);//terminates program execution included in the <stdlib.h>//break;default:printf("the choice is invalid\a\n");//\a means alarm//break;}}return 0;}
Also note the factorial case won't work after a certain set of integers since the factorial value exceeds the size of int
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