Printing a string of names in different lines - arrays

Question

I have recently started learning C, and I made this small piece of code, but it's not really working the way I wanted:
#include <stdio.h>
#include <string.h>
int main()
{
int i;
char a[] = "Bill Sarah Alice";
for (i = 0; a[i] != '\0'; i++)
{
if (a[i] != '\t' || a[i] != ' ')
{
printf("%c", a[i]);
}
putchar('\n');
}
return 0;
}
I wanted to print one name per line, but instead its printing one character per line. Can someone tell how should I fix it so it will work?

Answer 1

if(a[i] != '\t' || a[i] != ' '){
Every character is not tab or not space. So this if will be passed by every single character. You then output a newline after every single character. So this code is equivalent to this:
for(i=0; a[i] != '\0'; i++){
printf("%c", a[i]);
putchar('\n');
}
If you want to print each name on a line, you need to do something more like this:
for(i=0; a[i] != '\0'; i++){
if(a[i] == '\t' || a[i] == ' ')
putchar('\n');
else
printf("%c", a[i]);
}
putchar('\n');

Answer 2

Alternatively to other answers you can use isspace to detect spaces or tabs:
#include <ctype.h> // for isspace()
#include <stdio.h>
int main()
{
int i;
char a[] = "Bill Sarah Alice";
for (i = 0; a[i] != '\0'; i++)
{
if (!isspace(a[i])) // if it's not a space
{
printf("%c", a[i]); // print character
}
else
putchar('\n'); // if it is print a newline
}
}
Output:
Bill
Sarah
Alice

Answer 3

There are two issues in your code. First, the newline character will be printed on every run through the for loop; to fix this, put the putchar('\n'); line into an else block.
Second, your test condition is wrong and can never be false: the character cannot be both a tab and a space, so one of the != tests will always be true; to fix this, change the || to a &&.
int main()
{
int i;
char a[] = "Bill Sarah Alice";
for (i = 0; a[i] != '\0'; i++) {
if (a[i] != '\t' && a[i] != ' ') {
printf("%c", a[i]);
}
else {
putchar('\n');
}
}
return 0;
}

Answer 4

Within the for loop an output of the new line character '\n' is executed after printing each character in the string that is not equal to '\t' or to ' '.
if(a[i] != '\t' || a[i] != ' '){
printf("%c", a[i]);
}
putchar('\n');
Moreover the condition in the if statement shall be written at least like
if(a[i] != '\t' && a[i] != ' '){
^^^^
You need to output the new line character after a whole name is outputted. So if you are outputting a name character by character then you need one more inner loop.
Also the header <string.h> is redundant because neither declaration from the header is used in your program. So you may remove the directive
#include <string.h>
The algorithm can look the following way as it is shown in the demonstrative program below. It is implemented as a separate function.
#include <stdio.h>
void print_names( const char *s )
{
while ( *s != '\0' )
{
while ( *s == ' ' || *s == '\t' ) ++s;
while ( *s && *s != ' ' && *s != '\t' ) putchar( *s++ );
putchar( '\n' );
}
}
int main(void)
{
char a[] = "Bill Sarah Alice";
print_names( a );
return 0;
}
The program output is
Bill
Sarah
Alice
If to include the header <ctype.h>
#include <ctype.h>
then the function can be rewritten using the standard C function isblank that itself does the check whether a character is equal to the space character or to the tab character.
#include <stdio.h>
#include <ctype.h>
void print_names( const char *s )
{
while ( *s != '\0' )
{
while ( isblank( ( unsigned char )*s ) ) ++s;
while ( *s && !isblank( ( unsigned char )*s ) ) putchar( *s++ );
putchar( '\n' );
}
}
//...

Answer 5

What you want, is the function strtok(3).
strtok uses a delimiter string to return parts of the string. By using " " as a delimiter, you can easily extract the names. For how to use the function read the man page I linked above. Or read this article.
You can print the names one at a time using the following code
#include <stdio.h>
#include <string.h>
int main
(int argc, char *argv[], char *envp[])
{
char a[] = "Bill Sarah Alice";
char *tok = strtok (a, " ");
while (tok) {
puts (tok);
tok = strtok (NULL, " ");
}
return 0;
}