How to convert the first character of a std::string to lowercase...

hi,

I'm trying to convert the first character of a std::string to lowercase. I tried using Tolower, but it doesn't work :-(

example:

Code:

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string nEq1 = "Sporting", nEq2 = "Porto", idPlayer;

idPlayer = nEq1.at(0);
idPlayer += "1";

idPlayer //transform the first character of this std::string to lowercase????

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Can anyone help me?

You say you tried using tolower? Let's see what you tried.

hi hk_mp5kpdw...

i tried this:

Code:

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idPlayer.ToLower();

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and this:

Code:

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transform (idPlayer.begin(), tolower);

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and both don't work and give me errors :-(

What were the errors? Where did you get the idea for that second bit of code? Go back and look at it again, you just didn't follow the example fully. The first try won't work because ToLower() is not a function of the string class.

ups! i'm really lame :-(

i forgot the:

Code:

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#include <algorithm>

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after including algorithm, VS2005 was able to recognize the transform() and help me do what i really wanted to do...

Code:

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transform(idPlayer.begin(), idPlayer.end(), idPlayer.begin(), tolower);

---

Thanks anyway for the help...
I'll be more careful next time i ask for help.

Quote:

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Originally Posted by IndioDoido

ups! i'm really lame :-(

i forgot the:

Code:

---

#include <algorithm>

---

after including algorithm, VS2005 was able to recognize the transform() and help me do what i really wanted to do...

Code:

---

transform(idPlayer.begin(), idPlayer.end(), idPlayer.begin(), tolower);

---

Thanks anyway for the help...
I'll be more careful next time i ask for help.

---

I'm surprised that even compiled. tolower should be an overloaded function, so it needs a typecast. But even then that algorithm converts the entire string.

But you say you want to convert only the first characters, not the entire string. This is a three step process:
1)Obtain the character to be converted from the string.
2)Convert the character to lowercase
3)Replace the old character with the converted one.

That's the pseudo code, now write that in C++.

hi King Mir...

Quote:

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I'm surprised that even compiled. tolower should be an overloaded function, so it needs a typecast. But even then that algorithm converts the entire string.

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Yap...it didn't give me any compile error :S

I'm only copying the first character from the string...

Code:

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string nEq1 = "Sporting", nEq2 = "Porto", idPlayer;

idPlayer = nEq1.at(0);

---

and only then i'm converting it to lowercase.

By the way...if i've wanted something like this:
"SPORTING"
and transform into:
"sPORTING"

Wouldn't it be possible with:

Code:

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transform(idPlayer.begin(), idPlayer.end(), idPlayer.begin(), tolower);

---

??

Just use tolower on that character. Note that at() returns a char reference, so you need to use tolower directly on the result of at(0) or save it in a reference to char variable so that it will update that value in the string.

Quote:

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Originally Posted by IndioDoido

By the way...if i've wanted something like this:
"SPORTING"
and transform into:
"sPORTING"

Wouldn't it be possible with:

Code:

---

transform(idPlayer.begin(), idPlayer.end(), idPlayer.begin(), tolower);

---

??

---

You are passing begin...end to the transform() function, so why would you expect it to only affect the first character? It's going to affect the entire range. You COULD do:

Code:

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transform(idPlayer.begin(), idPlayer.begin(), idPlayer.begin(), tolower);

---

But that's a bit ridiculous to operate on a single character. If you want to change the first character, just do it.

Quote:

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Originally Posted by brewbuck

You are passing begin...end to the transform() function, so why would you expect it to only affect the first character? It's going to affect the entire range. You COULD do:

Code:

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transform(idPlayer.begin(), idPlayer.begin(), idPlayer.begin(), tolower);

---

But that's a bit ridiculous to operate on a single character. If you want to change the first character, just do it.

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You mean:

Code:

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transform(idPlayer.begin(), ++idPlayer.begin(), idPlayer.begin(), tolower);

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Or possibly saving idPlayer.begin() to a variable and incrementing that.

Otherwise you're operating on an empty list.

Oh, dear. std::transform works on a range. You want to change just one character, not a range.

Assign the result of calling tolower on the first character of the string to the first character?

Quote:

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Originally Posted by King Mir

You mean:

Code:

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transform(idPlayer.begin(), ++idPlayer.begin(), idPlayer.begin(), tolower);

---

Or possibly saving idPlayer.begin() to a variable and incrementing that.

Otherwise you're operating on an empty list.

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Yep. Bug!

wow, thanks alot guys!

I really didn't now how to use transform().
In C i simply used strlwr(), but now i have a pretty good idea on how transform() works in this case :-)