so i'm trying to write code under the following specs - enter a decimal number containing up to 3 numbers and decides if the number entered is a prime number. If more than 3 numbers are entered, program should output the message More than 3 characters and exit. If a non-numeric character is entered, the program should output the message Invalid input and exit. If the input is valid, your program should display either the message number entered is a prime number or the message number entered is not a prime number.
i'm really unsure not just how to calculate a prime number using loops but also where to input that into my program. I understand this is quite a basic question.
#include <stdio.h> #include <string.h> #define FALSE 0 #define TRUE 1 /* check string only contains decimal digits */ int numeric(char* string) { int i, valid; valid = TRUE; for (i = 0; i < strlen(string); i++) { if (string[i] < '0' || string[i] > '9') valid = FALSE; } return valid; } /* main function */ int main() { char number[4]; int count, toolong = FALSE; printf("Enter number: "); fgets(number, 4, stdin); if (number[strlen(number) - 1] == '\n') number[strlen(number) - 1] = '\0'; else while (getchar() != '\n') toolong = TRUE; if (toolong) { printf("More than 3 characters"); return 1; } if (!numeric(number)) { printf("'%s' is an invalid number\n", number); } printf("'%s' is a valid number\n", number); return 0; } Thank you :)
