如何检查字符串C中的空格？

Question

I am trying to have my program take a name as input from the user and then print out the initials of that name. ie tommy brown --> tb

What I have so far is this:

int main (void)
{

char scroll[100] = {"kang cheng junga"};
printf ("%c\n", *(scroll+2));

for (int i=0; i<100; i++)
{
    if (*(scroll+i)=" ")
    {
        printf (*(scroll+i+1));
    }
}

I keep getting this error:

error: incompatible pointer to integer conversion assigning to 'char' from 'char [2]'

[-Werror,-Wint-conversion] if (*(scroll+i)=" ")

error: using the result of an assignment as a condition without parentheses

[-Werror,-Wparentheses] if (*(scroll+i)=" ")

Can anyone tell me how I've screwed this up? I am having a hard time understanding how * and & function in a C. I am a beginner so I don't really know what I'm doing.

Answer 1

In addition to strtok , this is one time you can also make use of strpbrk to easily find each space :

#include <stdio.h>
#include <string.h>

int main (void) {

    char scroll[100] = "kang cheng junga";
    char *p = scroll;

    printf ("\n full name: %s\n", scroll);
    printf (" initials : %c", *p);

    while ((p = strpbrk (p, " ")))
            printf ("%c", *++p);

    printf ("\n\n");

    return 0;
}

Output

$ ./bin/initials

 full name: kang cheng junga
 initials : kcj

You can also eliminate the dependence on string.h with an alternative version that uses pointers alone:

#include <stdio.h>

int main (void) {

    char scroll[100] = "kang cheng junga";
    char *p = scroll;

    printf ("\n full name: %s\n", scroll);
    printf (" initials : %c", *p);

    while (*p++)
        if (*p == ' ' && *++p)
            printf ("%c", *p);

    printf ("\n\n");

    return 0;
}

Answer 2

The Error you are getting is because of the assignment operator (=) .

if (*(scroll+i)=" ")// assigning a value(blank)
{
    printf (*(scroll+i+1));
}

if (*(scroll+i) == ' ')//Comparing it with a value (blank)
{
    printf (*(scroll+i+1));
}

Answer 3

In C, = is assignment operator, and == is equality operator. You need to use the later one.

That said, there is a nice library function, named strtok() which can make your life easier. Just pass the string and a delimiter, (here, the space) and it will return the token to you, for which you can print the first character to get the initials.

Answer 4

along with strtok or strchr here is a simple way to implement , some boundary conditions are missing like name ending with single letter etc

#include <stdio.h>

int main (void)
{

        int i = 0;
        char scroll[100] = {"kang cheng junga"};
        char *p = scroll; // point to base
        printf("%c", *p ); // first letter is almost always certain
        while( *p != '\0' ) { // till end of String

                if ( *(p-1)     == ' ' && *(p+1) != '\0') { // If previous is space and next letter exists
                        printf("%c", *p );      // take it save it or print it
                }
                p ++ ; //proceed
        }

        return 0;
}