convert from upper to lower

Hello
please
1-what is the proplem with this code
2-how can i use fgets in this code
3- can i use BUFSIZ
which will be more faster BUFSIZ or strlen()

Code:

#include<stdio.h> #include<string.h> #include<stdbool.h> char toupper(char); char tolower(char); bool islower(char); bool isupper(char); int main(){ char str[20]; int i; printf("Enter any string:"); gets(str); for(i=0;i<=strlen(str);i++){ if(islower(str[i])==1) toupper(str[i]); else if(isupper(str[i])==1) tolower(str[i]); } printf("%s\n",str); return 0; } bool islower(char ch){ if(ch>='a'&&ch<='z') return 1; else return 0; } bool isupper(char ch) { if (ch<='A' && ch>='Z') return 1; else return 0; } char toupper(char ch) { if (ch <= 'a' && ch >= 'z') ch=ch+32; return ch; } char tolower(char ch) { if (ch <= 'A' &&ch >= 'Z') ch=ch-32; return ch; }

What is BUFSIZ? A macro of stdio.h.
strlen is a function. So, I would go for strlen. As a matter of fact, I would cache the result of it, before going to line 13.
In code, you have

Code:

for(..;i<strlen(..);..)

I would have

Code:

int len = strlen(...); for(.. ; i < len ; ..)

because you don't need every time the loop is executed the strlen function to be invoked again and again ;)

>What is the program with this code?
What do you think it is? :)

You must use fgets! gets must not be used.
What you should do, is to use fgets instead of gets.

i used fgets and made new var for strlen()
but the same proplem :frown:

Code:

#include<stdio.h> #include<string.h> #include<stdbool.h> char toupper(char); char tolower(char); bool islower(char); bool isupper(char); int main(){ char str[20]; int i; printf("Enter any string:"); fgets(str,20,stdin); int len=strlen(str); for(i=0;i<len;i++){ if(islower(str[i])==1) toupper(str[i]); else if(isupper(str[i])==1) tolower(str[i]); } printf("%s\n",str); return 0; } bool islower(char ch){ if(ch>='a'&&ch<='z') return 1; else return 0; } bool isupper(char ch) { if (ch<='A' && ch>='Z') return 1; else return 0; } char toupper(char ch) { if (ch <= 'a' && ch >= 'z') ch=ch+32; return ch; } char tolower(char ch) { if (ch <= 'A' &&ch >= 'Z') ch=ch-32; return ch; }

thanks for help

It would help us, and you, immensely if you actually told us what the problem is!

i need program that i input string like this
TOSst!@
and output
tosST!@

the proplem in source that if write anything it just output it the same

Your "toupper()" and "tolower()" functions return the modified character value. Therefore, in "main()", you want to assign the result of those functions to the current string index.

Also, you have redundant checks in your "toupper()" and "tolower()" functions (they're already checked in your "isupper()" and "islower()" functions).

Another thing - carefully go through your code and double-check all <= and >= operators; you seem to have made a few mistakes with those.

And one last thing - those function names are already reserved, so if you're writing your own versions, make the names unique.

Code:

main.c|4|warning: conflicting types for built-in function 'toupper'| main.c|5|warning: conflicting types for built-in function 'tolower'| main.c|6|warning: conflicting types for built-in function 'islower'| main.c|7|warning: conflicting types for built-in function 'isupper'| ||=== Build finished: 0 errors, 4 warnings ===|

Quote:

Originally Posted by tost

i need program that i input string like this
TOSst!@
and output
tosST!@

Wait! How did YOU do this? HOW did you change TOSst!@ to tosST!@?

The steps you took to do it, are the same steps that the computer might take to do it, (with just a few wrinkles).

Study how you did it, and write down each little step of logic you took, and THAT can be the same steps of logic your program can take, as well.

:cool:

Thanks i forgot that c++ has toupper tolower function so i changed all name
i removed the second check in to_lower to_upper
and <= >=;

could you tell me what IDE or compiler you use?
i still have the same proplem :(

Code:

#include<stdio.h> #include<string.h> #include<stdbool.h> char to_upper(char); char to_lower(char); bool is_lower(char); bool is_upper(char); int main(){ char str[20]; int i; printf("Enter any string:"); fgets(str,20,stdin); int len=strlen(str); for(i=0;i<len;i++){ if(is_lower(str[i])==1) to_upper(str[i]); else if(is_upper(str[i])==1) to_lower(str[i]); } printf("%s\n",str); return 0; } bool is_lower(char ch){ if(ch>'a'&&ch<'z') return 1; else return 0; } bool is_upper(char ch) { if (ch<'A' && ch>'Z') return 1; else return 0; } char to_upper(char ch) { ch=ch+32; return ch; } char to_lower(char ch) { ch=ch-32; return ch; }

mr.Adak
i will let user input in char array and i will check every char if it upper then change to lower if it lower change to upper and the ascii symbol normal
that's my logic can you write to me how you think when you get programming proplem ?
i mean now i have proplem like 123456 and i need to get it like 1 2 3 4 5 6
do not write the program please but just tell me how you think about that?

As matticus said, you have to retrieve what your functions return in main ;) (otherwise, they are "lost").

Quote:

Originally Posted by Matticus

Your "toupper()" and "tolower()" functions return the modified character value. Therefore, in "main()", you want to assign the result of those functions to the current string index.

That's how you would update the string in "main()."

--------

Code:

bool is_upper(char ch) { if (ch<'A' && ch>'Z') return 1; else return 0; }

You need to think about the logic. You seem to want this function to return 1 if the character is uppercase, but your logic says "return 1 if the character is less than 'A' and greater than 'Z'" (which is impossible, by the way).

Also, on the standard ASCII chart, lowercase letters come after uppercase letters, so to make a lowercase into an uppercase, you would have to subtract (not add) a value.

--------

Take a deep breath, slow yourself down a bit, and go through your code slowly and thoroughly, making sure you understand what each line of code is doing.

mr std10093
i red the topic about why not using BUFSIZ it's size changeable from compiler to other
so where can i use it socket programming or what ?
i mean best situation to use BUFSIZ an nothing else

:wink:
that's right no update happen in the main function it just change the value then nothing
The correct code

Code:

#include<stdio.h> #include<string.h> #include<stdbool.h> char to_upper(char); char to_lower(char); bool is_lower(char); bool is_upper(char); int main(){ char str[20]; int i; printf("Enter any string:"); fgets(str,20,stdin); int len=strlen(str); for(i=0;i<len;i++){ if(is_lower(str[i])==1) str[i]=to_upper(str[i]); else if(is_upper(str[i])==1) str[i]=to_lower(str[i]); } printf("%s\n",str); return 0; } bool is_lower(char ch){ if(ch>=97&&ch<=122) return 1; else return 0; } bool is_upper(char ch) { if (ch>=65 && ch<=90) return 1; else return 0; } char to_upper(char ch) { return ch-32; } char to_lower(char ch) { return ch+32; }

thanks
mr.Matticus :wink:

mr.Adak

mr.std10093

now i have this Q
1-what does mr.std10093 mean by?
It’s 2013 and I still use printf() for debugging.

2- best situation that i use BUFSIZ MACRO ?

3-Q like this 12345 need to out put 1 2 3 4 5
how can i think in problem like this ?

Realy thanks for help

Quote:

Originally Posted by tost

Code:

bool is_lower(char ch){ if(ch>=97&&ch<=122) return 1; else return 0; } bool is_upper(char ch) { if (ch>=65 && ch<=90) return 1; else return 0; } char to_upper(char ch) { return ch-32; } char to_lower(char ch) { return ch+32; }

No, don't do that. Why did you change it from the perfectly descriptive 'A' and 'Z' etc to 65 and 90?
You'd best change those back.

Also, that magic number 32 is bad as well. You could instead return ch + 'A' - 'a'; for to_upper, for example.

Quote:

Originally Posted by tost

mr.Adak
i will let user input in char array and i will check every char if it upper then change to lower if it lower change to upper and the ascii symbol normal
that's my logic can you write to me how you think when you get programming proplem ?
i mean now i have proplem like 123456 and i need to get it like 1 2 3 4 5 6
do not write the program please but just tell me how you think about that?

123456 - The input

My thinking goes like this:

#1.
for every digit in the set of digits, print it, then print a space

#2.
for(every digit in the set of digits)
....print the digit and a space

#3.
for(i equals first digit, i is less than or equal to 6, increment i)
....printf(the digit and 1 space)

Ready to code up the loop.

It's odd to take it through these steps, because with practice, you just say "got it", and code it. But the process REALLY comes into play with any problem where you don't have an answer.

Failing anything better, start with how YOU would do it, and take that logic step by step, to your program.

If you are using an integrated editor for your compiler, it should have a "debugger" option that will allow you to step through your code, one line at a time, and at the same time, watch several variable values to see how they're changing, etc.

printing out a quick variable is a very valuable debugging aid, as well. Even if you're not running the program in "debug" mode.

Quote:

Originally Posted by iMalc

No, don't do that. Why did you change it from the perfectly descriptive 'A' and 'Z' etc to 65 and 90?
You'd best change those back.

Also, that magic number 32 is bad as well. You could instead return ch + 'A' - 'a'; for to_upper, for example.

i changed it then i changed it to 'A','Z'
thank you :)

Quote:

Originally Posted by Adak

123456 - The input

My thinking goes like this:

#1.
for every digit in the set of digits, print it, then print a space

#2.
for(every digit in the set of digits)
....print the digit and a space

#3.
for(i equals first digit, i is less than or equal to 6, increment i)
....printf(the digit and 1 space)

Ready to code up the loop.

It's odd to take it through these steps, because with practice, you just say "got it", and code it. But the process REALLY comes into play with any problem where you don't have an answer.

Failing anything better, start with how YOU would do it, and take that logic step by step, to your program.

i'm going to do that practice and practice
i need more problems that let me learn

Working

Code:

#include<stdio.h> #include<string.h> int main() { char arr[100]; int i=0; fgets(arr,100,stdin); int x=strlen(arr); for(i=0;i<x;i++){ printf(" %c",arr[i]); } return 0; }

Working

Code:

#include<stdio.h> #include<string.h> int main() { char arr[100]; int i=0; fgets(arr,100,stdin); while(i<strlen(arr)){ printf(" %c",arr[i]); i++; } return 0; }

Not Working i used debugger step by step it go ahead to return 0 Why?

Code:

#include<stdio.h> #include<string.h> int main() { char arr[100]; int i; fgets(arr,100,stdin); for(i=0;i!='\0';i++){ printf(" %c",arr[i]); } return 0; }

Not Working i used debugger step by step it go ahead to return 0
Why?
loop till find the Null terminator ?

Code:

#include<stdio.h> #include<string.h> int main() { char arr[100]; int i=0; fgets(arr,100,stdin); while(i!='\0'){ printf(" %c",arr[i]); i++; } return 0; }

Not Working i used debugger step by step it go ahead to return 0

Code:

#include<stdio.h> #include<string.h> int main() { char arr[100]; int i=0; fgets(arr,100,stdin); while(arr){ if(i!='\0'){ printf(" %c",arr[i]); i++;} else return 0; } return 0; }

in the first,second Code i used strlen() that will count the Null terminator
i mean it is the same idea with the other 3 code
so what is the problem

This:

Code:

for(i=0;i!='\0';i++){

is incorrect. You're telling the for loop to quit if i does not equal '\0'. But i is an int, and i =0 is the equivalent of i='\0', so the test evaluates to true, causing the loop to quit , before it loops. :(

Add this line inside the for loop. See how many times it prints the value of i:

Code:

printf("i equals: %d\n",i);

That's one of the beauties of programming - you can test your own ideas out.