C program to find total number of digits [closed] - c

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I wrote this program to find the total number of digits from a line of text entered by user. I am having error on using getchar(). I can't seem to figure out what am I doing wrong?
#include <stdio.h>
#define MAX_SIZE 100
void main() {
char c[MAX_SIZE];
int digit, sum, i;
digit, i = 0;
printf("Enter a line of characters>");
c = getchar();
while (c[i] != '\n') {
digit = 0;
if (c [i] >= '0' && c[i] <= '9') {
digit++;
}
}
printf("%d\n", digit);
}
I will be adding all the digits I found using sum variable. but I am getting error on getchar() line. HELP??

Answer 1

You can enter a "line of text" without using an array.
#include <stdio.h>
#include <ctype.h>
int main(void) { // notice this signature
int c, digits = 0, sum = 0;
while((c = getchar()) != '\n' && c != EOF) {
if(isdigit(c)) {
digits++;
sum += c - '0';
}
}
printf("%d digits with sum %d\n", digits, sum);
return 0;
}
Note that c is of type int. Most of the library's character functions do not use char type.
Edit: added the sum of the digits.

Answer 2

Weather Vane's answer is the best and simplest answer. However, for future reference, if you want to iterate (loop through) an array, it would be easier to use a for loop. Also, your main function should return an int and should look like this: int main(). You will need to put a return 0; at the end of your main function. Here is a modified version of your program that uses a for loop to loop through the character array. I used the gets function to read a line of characters from the console. It does wait for the user to enter the string.
#include <stdio.h>
#define MAX_SIZE 100
int main()
{
char c[MAX_SIZE];
int digit = 0;
printf("Enter a line of characters>");
gets(c);
for (int i = 0; i < MAX_SIZE; i++)
{
if (c[i] == '\n') break; // this line checks to see if we have reached the end of the line. If so, exit the for loop (thats what the "break" statment does.)
//if (isdigit(c[i])) // uncomment this line and comment or delete the one below to use a much easier method to check if a character is a digit.
if (c [i]>= '0' && c[i] <= '9')
{
digit++;
}
}
printf("%d\n", digit);
return 0;
}

Answer 3

An easy of getting the number of digits in an integer is the use of log10() function which is defined in math.h header. Consider this program
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
int main (int argc, const char *argv[]) {
system("clear");
unsigned int i, sum = 0, numberOfDigits;
puts("Enter a number");
scanf("%u", &i);
numberOfDigits = (int) (log10(x) + 1);
system("clear");
while(i != 0) {
sum += (i % 10);
i /= 10;
}
fprintf(stdout, "The sum is %i\n", sum);
fflush(stdin);
return 0;
}