Thread: Replacing lowercase letter with the '@' symbol

Hey guys, I'm new to this forum and am just starting to learn C programming. I have a couple questions for my assignment and was wondering if I could get some help.

a) Write a C program that reads characters from standard input and replaces every lowercase a with the "at" symbol (@) before outputting the characters to standard output. For example, if your program is called a2at, the you could use the program as follows

eg. $ echo "This is an easy problem" | ./a2at
This is @n e@sy problem

b) Write a C program that reads from standard input and counts the number of uppercase letters. If your program is called count_upper, the you could use it as follows

eg. $ echo "Also an EASY problem" | ./count_upper
5

Any help would be greatly appreciated. Thank you.

I have a couple questions for my assignment and was wondering if I could get some help.

No you have provided absolutely *zero* questions. Instead you've just dumped your assignment on the board, apparently expecting us to do it for you. You might want to read this: Announcements - General Programming Boards

He clearly asked for help, not for us to do it for him. Greeting a first timer on the board, I hope your welcome will be as warm as your reply was not ^^^^.

We do get a lot of that "let me dump this on you and hope you'll do it for me", kind of posts. Hope you understand.

Welcome to the board, GWST11, and let's start with the first problem, only. What are you stuck on?

Code:

#include <ctype.h>

/* ... */

for (/* */) {
    if (islower(/* */)) {
   
    }
}

This might help you get started...

Thank you guys for the replies. Obviously my intention was not to have you guys do the assignment for me, I understand the rules and ethics, so I apologize if I sounded that way. I think I asked the question way too early, so I'm going to do more tutorials and continue practicing. And if I get really stuck then I will come back to this board, thanks for the head start memcpy.

a) Write a C program that reads characters from standard input and replaces every lowercase a with the "at" symbol (@) before outputting the characters to standard output. For example, if your program is called a2at, the you could use the program as follows

eg. $ echo "This is an easy problem" | ./a2at
This is @n e@sy problem

THIS IS WHAT I HAVE SO FAR:

Code:

#include <stdio.h>
#include <ctype.h>
    void main()
    {
    int i =0;
        char s[1024];
        char c;
        int n;

 while( scanf( "%c", c))
 {
 s[i] = c;
i++;
}
}

for (i = 0; i < strlen(s); i++)
{
c = s[i];

if (islower(c))
{
 n = n + 1;
}
printf("number of upper case letters is %d", strlen(s) - n);
}

I am stuck now, I don't what the problem is, but maybe it has something to do with the strlen? Can anyone give me a hint, thanks.

Originally Posted by GWST11

Code:

...
for (i = 0; i < strlen(s); i++)
{
c = s[i];

if (islower(c))
{
 n = n + 1;
}
printf("number of upper case letters is %d", strlen(s) - n);
}

Using strlen like that is bad.

since strlen function is something like

Code:

int 
strlen(const char *s)
{
   const char *b =s;
   while(*b)
      b++;
   return(b-s);
}

so if your string is 100 chars long then your for(i=0;i<strlen(some_string); i++ ) will look at all 100 chars 100 times for a total of 10K looks just from the strlen.




its much better to use some thing like
for(i=0;some_string[i]; i++)