how to use strtok to print a binary number? - c

Question

So im trying to get a binary number from using the strtok function to iterate through a user inputted string. If the user inputs alpha it prints a 0 and if the user inputs beta it will output a 1.So if a user types in "alpha beta alpha beta alpha" the output should be "01010". I have the following code but im not sure where im going wrong as it is not doing the behavior i described
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
int main(int argc, char * argv[])
{
char userinput[250];
long binaryarray[250];
char *token;
int counter = 0;
long binarynumber = 0 ;
printf("enter alpha or beta");
scanf("%s", userinput);
token = strtok(userinput, " ");
while (token != NULL)
{
if(!strcmp(token, "alpha"))
{
binaryarray[counter] = 0;
counter += 1;
}
if(!strcmp(token, "beta"))
{
binaryarray[counter] = 1;
counter += 1;
}
token = strtok(NULL, " \0");
}
for(int i = 0; i < counter; i++)
{
binarynumber = 10 * binarynumber + binaryarray[i];
}
printf("%ld", binarynumber);
}
How would I fix this issue?

Answer 1

The problem is, for
scanf("%s",userinput);
the scanning stops after encountering the first whitespace. So, it cannot scan and store an input like
alpha beta alpha beta alpha
separated by whitespace. Quoting C11, chapter §7.21.6.2
s
Matches a sequence of non-white-space characters.
Possible Solution: You need to use fgets() to read the user input with whitespaces.

Answer 2

As already said by #SouravGhosh you should use fgets to store the whole string inserted by user with white spaces.
#include <stdio.h>
#include <string.h>
int main(int argc, char * argv[])
{
char userinput[250] = {0};
char binaryarray[250];
char* token;
size_t counter = 0;
printf("enter alpha or beta");
fgets(userinput, sizeof(userinput), stdin);
token = strtok(userinput, " \n\0");
while (( token != NULL) && (count < sizeof(binaryarray)))
{
if(!strcmp(token,"alpha"))
{
binaryarray[counter] = '0';
counter++;
}
else if(!strcmp(token,"beta"))
{
binaryarray[counter] = '1';
counter++;
}
token = strtok(NULL, " \n\0");
}
for(size_t i=0 ; i< counter; i++)
{
printf("%c", binaryarray[i]);
}
printf("\n");
}
But you have other problems:
Your tokens should be " \n\0" to match all possible chars between words.
All tokens must be checked with the first strok in case of a single input, so no whitespaces
Using an int to calculate your "binary" and print it with "%ld" format specifier does not print leading zeros. You can directly store chars into the buffer.