CODEWITHSUNDEEP
c
Module
Module

Reputation: 250

Having trouble converting a whole sentence from uppercase to lower case in C

My code is correct as I can see it has no errors at all, but when I execute it and say for instance I type in "MY NAME IS JACK" it only converts "MY" to lowercase.

#include<stdio.h>

#include<string.h>

int main()

{

char str[20];

int i;

  printf("Enter any string->");

  scanf("%s",&str);

  for(i=0;i<=strlen(str);i++){


      if(str[i]>=65&&str[i]<=90)

       str[i]=str[i]+32;

  }

  printf("\nThe string in lower case is->%s",str);

  return 0;

}

Upvotes: 0

Views: 1125

Answers (5)

John Bode
John Bode

Reputation: 123558

As others have pointed out, scanf using the %s conversion specifier will stop reading intput at the first whitespace character. If you want to read in the whole line, use fgets instead:

#include <stdio.h>
#include <ctype.h>
#include <string.h>
...
if ( fgets( str, sizeof str, stdin ) != NULL )
{
  /**
   * chop off the newline if it's present
   */
  char *newline = strchr( str, '\n' );
  if ( newline )
  {
    *newline = 0;
  }

  /**
   * Convert the string to lower case.
   */
  for ( int i = 0; str[i] != 0; i++ )
    str[i] = tolower( str[i] );
}

Note - if there isn't a newline in the buffer, that means that the user typed in a string that was longer than the buffer could hold, meaning there's leftover data in the input stream. You'll probably want to issue a warning and consume that leftover input (usually by repeatedly calling fgets or getchar and stopping when you see a newline character).

Upvotes: 3

photoionized
photoionized

Reputation: 5232

Change

scanf("%s",&str);

to

scanf("%[^\n]",str);

and your code should work. %s reads until whitespaces. Using [^\n] makes scanf read into the str variable until it encounters a newline. Also, don't pass the address of str, just str itself.

Upvotes: 0

EJ Dogar
EJ Dogar

Reputation: 68

You can try the following code for it as well once you are done with your input.

void convertToUpperCase(char *sPtr)
{
  while(*sPtr != '\0')
  {
     if (islower(*sPtr))
          *sPtr = toupper(*sPtr);
   }
}

Upvotes: 1

Younggun Kim
Younggun Kim

Reputation: 986

First,

scanf() expects argument of type 'char ' but you are passing char ()[20]. Just pass 'str'.

Second,

This is just suggestion. Try to use isalpha() or issuper(), islower()

Upvotes: 0

OnlineCop
OnlineCop

Reputation: 4069

The scanf description for the %s format defines it as:

Any number of non-whitespace characters, stopping at the first whitespace character found. A terminating null character is automatically added at the end of the stored sequence.

So you are asking for the first non-whitespace text within str, which is "MY". Once it hits that space, it stops.

What would be better for your usage: reading the entire line in at once, or putting your scanf into a loop so you can read successive words?

Upvotes: 1

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