i need to check if the variable in the valid parameters is a digit, but i dont know how to make a char a int to checkCode:int main() { const char* filename = "prefixRanges.txt"; char str[10]; int area; FILE* fp; printf("Enter:\n"); scanf("%s", str); valid(str); //fp = open(filename); //registered(fp, area); return 0; } int valid(const char* str){ printf(str); }
i tried this
but i get a random numberCode:int valid(const char* str){ int n = (int)str; printf("%d", n); }
you may use atoi();
requires the stdlib.h header.Code:int n; n = atoi(str);
i was thinking atoi but after i check if they are digits i need to use each digit seperately
ie. if i have 196, i may want to do this 1+9+6 to get the sum
you can go back and use str to manipulate it as a string. That way you can use each digit separately.
but it can't use the string like an array, it wont work
like i tried str[0] but that won't work
a c string IS an array.
str[0] is a char
I copied it from the last program in which I passed a parameter, which would have been pre-1989 I guess. - esbo
>like i tried str[0] but that won't work
Code:#include <ctype.h> . . if (isdigit(str[0])) { /* Digit found }
In this function str is a pointer which holds as its value the memory address of a char. We programmers usually look at a char* variable as a string variable, but when you get down to basics it is only a variable that holds the address of a char. string manipulation functions from string.h (such as strlen() and strcpy() ) know how to use the address in the context of a string, but you are still only providing them with the address of a character.Originally Posted by bigmac(rexdale)
By casting to an int as in int n = (int)str;, you are converting the address into an integer representation, and then assigning that integer representation to the variable n. So when you print n, although it looks random to you, you are printing the address that str happens to be pointing at.
abachler: "A great programmer never stops optimizing a piece of code until it consists of nothing but preprocessor directives and comments"
You can use isdigit() function to check it and after converting it to digit with atoi() you can do-
num=your digit
sum=0
loop begin where you check num is 0 or not
divres=num/10
sum=sum+(num%10)
num=divres
loop end
so you get also the sum of digits, I think it helps you.
