Why does my char array return different characters for each index in C

Question

I have a string, which I declare as char myStr[ ] = "5.3 2.4 1.8".

When I print it directly with printf, it seems to print what I would expect. However, when I print each index, instead of getting myStr[3] = ' ' , I get myStr[3] = 32. Below is my code and output. I would like to know why this is happening, and how I can ensure that the spaces will be interpreted as space and not the number 32?

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

int words(char myStr[ ]);

int main(){
char myStr[ ] = “5.3 2.4 1.8”;
printf(“myStr is: %s\n", myStr);
words(myStr);
}

int words(char myStr[ ]){
  int i, length, count=0, prev=0;
  length= strlen(myStr);

   printf("The length of myStr is: %d\n", length);

  for (i=0; i<length; i++){
   printf("The %d letter of myStr is: %d\n", i, myStr[i]);
   if (myStr[i] != ' '){
      if (prev=0)
        count++;
      else
        prev=1;
    }
    else
      prev=0;
  }
  return count;
}

Below is the output:

The first line is: 5.3 2.4 1.8
The length of myStr is: 11
The 0 letter of myStr is: 53
The 1 letter of myStr is: 46
The 2 letter of myStr is: 51
The 3 letter of myStr is: 32
The 4 letter of myStr is: 50
The 5 letter of myStr is: 46
The 6 letter of myStr is: 52
The 7 letter of myStr is: 32
The 8 letter of myStr is: 49
The 9 letter of myStr is: 46
The 10 letter of myStr is: 56

Thank you for any advice!

Use %c to interpret it as a character instead of %d which will print the ASCII value of the character. Also change if (prev=0) to if (prev==0). = is the assignment operator, and is different from ==, which is the comparision operator. — Spikatrix
– Spikatrix, Commented Mar 13, 2015 at 2:53
32 is the ASCII (Unicode) value for space or blank. Just like the digits have values between 48 and 57, blanks are 32 and decimal points are 46. — Jonathan Leffler
– Jonathan Leffler, Commented Mar 13, 2015 at 2:55

simon_xia · Accepted Answer · 2015-03-13 03:07:15Z

2

Cause each char is stored as an 8-bit-width integer from the memory's perspective, according to ASCII table

In printf use %c will get char and %d will get the int

e.g:

char a = 'A';
printf("%c\n", a);
printf("%d\n", a);

the output will be:

A
65

the piece of a's memory just like

        +-----------+                
    a   | 01000001  |                
        +-----------+

two different results just because the output format of printf

edited Mar 13, 2015 at 3:07

answered Mar 13, 2015 at 2:55

simon_xia

2,5541 gold badge23 silver badges32 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

user2808302 Over a year ago

Thank you @simon_xia. One side question I notice is the line if (myStr[i] != ' '). For some reason, this evaluates for false each time, even though myStr is character type. So, when I run the int words() function, I get zero words, when I should get 3 (since there are two spaces in myStr "5.3 2.4 1.8"). Do you know how I could get my program to recognize myStr[3] as a ' ' , so that the statement if (myStr[i] != ' ') will evaluate to true twice, and return a word count of three? Many thanks again...

M.M Over a year ago

@user2808302 the mystr[i] != ' ' is working correctly. You're probably confused because if (prev=0) doesn't do what you think it does

simon_xia Over a year ago

@user2808302 the statment if (prev=0) should be if (prev==0)

simon_xia Over a year ago

PS: It's a good practice to use int words(char *myStr); instead of int words(char myStr[ ]); @user2808302

Bill Lynch · Accepted Answer · 2015-03-13 02:58:24Z

1

If we look at the table of format strings for printf(), we see that if we want to print an integer we would use %d. You claim that you would like to print a character. Which is %c.

So, let's fix your call to printf():

printf("The %d letter of myStr is: %c\n", i, myStr[i]);

answered Mar 13, 2015 at 2:58

Bill Lynch

82.3k16 gold badges132 silver badges181 bronze badges

Collectives™ on Stack Overflow

Why does my char array return different characters for each index in C

2 Answers 2

4 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

4 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related