recursive functions of 1)strcmp 2)reverse a string

[kalar]

I need two recursive functions
1) the first must do the job of strcmp
I want to give me some tips about this such as example what am i supposed to compare the first character of each string and return the result? or all the characters? how strcmp works?

2)the second must print a string passed as an argument reverse
I make a try, but it does not print me the first character

#include <stdio.h>
#include <string.h>
 
void rev(char *p);
 
int main(void)
{ 
 char *k="ple";
 rev(k);
 
 return 0;
}
 
void rev(char *p)
{
 int l;
 
 l=strlen(p)-1;
 
if(l==0)
  return;
 else 
  rev(++p);
  printf("%c",*p);  
 
}

[Savage]

I need two recursive functions
1) the first must do the job of strcmp
I want to give me some tips about this such as example what am i supposed to compare the first character of each string and return the result? or all the characters? how strcmp works?

2)the second must print a string passed as an argument reverse
I make a try, but it does not print me the first character

#include <stdio.h>
#include <string.h>
 
void rev(char *p);
 
int main(void)
{ 
 char *k="ple";
 rev(k);
 
 return 0;
}
 
void rev(char *p)
{
 int l;
 
 l=strlen(p)-1;
 
if(l==0)
  return;
 else 
  rev(++p);
  printf("%c",*p);  
 
}

1.How strcmp works.

How do you compare two strings?

If you find two strings that have different length,would you bother comparing each letter when there is NO WAY that those string would be the same?

I think that you can figure it out from this.

Now,after this(sorry,if I sounded rude) can you tell me how strcmp works?

Savage

[kalar]

1.How strcmp works.

How do you compare two strings?

If you find two strings that have different length,would you bother comparing each letter when there is NO WAY that those string would be the same?

I think that you can figure it out from this.

Now,after this(sorry,if I sounded rude) can you tell me how strcmp works?

Savage

Thanks but i think that strcmp don't compare the two strings with base the length of the strings.

edit:i find this about the return of strcmp
A value greater than zero indicates that the first character that does not match has a greater value in str1 than in str2

I will make a try

Anyone about the second?

[Savage]

Thanks but i think that strcmp don't compare the two strings with base the length of the strings.

It compares each letter from one string with corresponding letter from the second string,but only if lengths are equal.

Savage

[JosAH]

It compares each letter from one string with corresponding letter from the second string,but only if lengths are equal.

Savage

No it doesn't, e.g. "b" > "aaaa" but the length of "b" is shorter than the length
of "aaaa".

kind regards,

Jos

[kalar]

I found about strcmp that works like a dictionary
any idea about 2?

[Savage]

I need two recursive functions
1) the first must do the job of strcmp
I want to give me some tips about this such as example what am i supposed to compare the first character of each string and return the result? or all the characters? how strcmp works?

2)the second must print a string passed as an argument reverse
I make a try, but it does not print me the first character

#include <stdio.h>
#include <string.h>
 
void rev(char *p);
 
int main(void)
{ 
 char *k="ple";
 rev(k);
 
 return 0;
}
 
void rev(char *p)
{
 int l;
 
 l=strlen(p)-1;
 
if(l==0)
  return;
 else 
  rev(++p);
  printf("%c",*p);  
 
}

Switch postiitons of rev(++p) and printf(..)

Savage

[kalar]

Switch postiitons of rev(++p) and printf(..)

Savage

this don't work
the code that i post prints the string reverse except the first character

[letmetry]

this don't work
the code that i post prints the string reverse except the first character

Modify the code in line no.18 like this,

l = strlen(p);

instead of

l = strlen(p) - 1;

[kalar]

Modify the code in line no.18 like this,

l = strlen(p);

instead of

l = strlen(p) - 1;

thanks but also don't work

[letmetry]

thanks but also don't work

Also, modify the last line as given below,

printf("%c",*(p-1));

[kalar]

Also, modify the last line as given below,

printf("%c",*(p-1));

yes worked but why *(p-1)?

[Ganon11]

Because you increment the pointer p in the function call, it now points to the second letter. You need to use *(p-1) to point it back to the char you wanted to print.

[weaknessforcats]

It compares each letter from one string with corresponding letter from the second string,but only if lengths are equal.

Not true.

strcmp compares correspoding characters until there is a mismatch and one of the values is not a null terminator. If one is a null terminator, then if the other is also, the strings are equal. Otherwise, the difference between the first argument less the second argument is returned.

Keep in mind a scan of the entire string is required to get the length. In that amount of time the compare could have been done.

strcmp is about 5 lines of code.