c - Using if statement instead of default of switch case -

is correct use if statement before opening switch case , avoid using default keyword? example want program takes input number of month , tells name. code uses switch case statement:

#include <stdio.h> #include <stdlib.h>  main() {     int month;     printf("insert number of month , program return name");     scanf("%i", &month);     switch (month) {       case (1):         printf("the month january");         break;       case (2):         printf("the month february");         break;       case (3):         printf("the month march");         break;       case (4):         printf("the month april");         break;       case (5):         printf("the month may");         break;       case (6):         printf("the month june");         break;       case (7):         printf("the month july");         break;       case (8):         printf("the month august");         break;       case (9):         printf("the month september");         break;       case (10):         printf("the month october");         break;       case (11):         printf("the month november");         break;       case (12):         printf("the month december");         break;       default:         printf("not valid");     }     system("pause");     return 0; } 

then, wondering if can put non-validity condition in if statement rather in default keyword. me seems correct since want verify value before program executes switch case statement. think, correct? if i'm not asking much, please tell me why?

the code if statement:

#include <stdio.h> #include <stdlib.h>  main() {     int month;     printf("insert number of month , program return name");     scanf("%i", &month);     if (month >= 1 && month <= 12) {         switch (month) {           case (1):             printf("the month january");             break;           case (2):             printf("the month february");             break;           case (3):             printf("the month march");             break;           case (4):             printf("the month april");             break;           case (5):             printf("the month may");             break;           case (6):             printf("the month june");             break;           case (7):             printf("the month july");             break;           case (8):             printf("the month august");             break;           case (9):             printf("the month september");             break;           case (10):             printf("the month october");             break;           case (11):             printf("the month november");             break;           case (12):             printf("the month december");             break;           default:;         }     } else {         printf("not valid");     }     system("pause");     return 0; } 

thank , sorry english not mother tongue. let me know if haven't explained myself clearly.

both approaches valid , equivalent except few details:

• the way define main obsolete. not compile c99 compiler in strict mode. use int main(void) or int main(int argc, char *argv[]).
• test return value of scanf(). if type cannot parsed number, scanf() return 0 or eof if close input stream, , rest of code use uninitialized value of month.
• it neither useful nor idiomatic parenthesize value in case clauses. remove them.
• it safer add break; statement @ end of last clause in switch statement, default or not. if ever add clause, wont risk omitting it.
• remove default:; clause second code, useless , surprising.

the reason why second approach might more indicated in case want different if input out of range, such restarting input operation. if statement allow separate these situations correctly, whereas using default clause might not appropriate:

for (;;) {     int n, month;     printf("enter number between 1 , 12: ");     n = scanf("%d", &month);     if (n == eof) {         printf("unexpected end of file\n");         exit(1);     }     if (n != 1) {         printf("invalid input\n");         scanf("%*[^\n]%*c"); /* flush pending input */         continue;     }     if (month >= 1 && month <= 12) {         switch (month) {           case 1:              printf("the month january\n");             break;           ...           case 12:              printf("the month december\n");             break;         }         handle_month(month);  // perform other tasks         break;     } else {         printf("invalid month number\n");     } }