C言語、文章内での文字数のカウント

Question

学校の課題で、文章内での文字数の数え方を作るC言語のプログラミングが全くわかりません。全くのプログラミング初心者です。助けてください

（文章）
You can sit before the desk (or in front of the desk). The professor can sit on
the desk (when he's being informal) or behind the desk, and then his feet are
under the desk or beneath the desk. He can stand beside the desk (meaning next
to the desk), before the desk, between the desk and you, or even on the desk (if
he's really strange). If he's clumsy, he can bump into the desk or try to walk
through the desk (and stuff would fall off the desk). Passing his hands over the
desk or resting his elbows upon the desk, he often looks across the desk and
speaks of the desk or concerning the desk as if there were nothing else like the
desk. Because he thinks of nothing except the desk, sometimes you wonder about
the desk, what's in the desk, what he paid for the desk, and if he could live
without the desk. You can walk toward the desk, to the desk, around the desk, by
the desk, and even past the desk while he sits at the desk or leans against the
desk.

Comments

[SaitoAtsushi]

「全くわからない」というのは要するに入門書の頭から全部解説する必要があるという意味ですのでここで回答するのは非現実的です。
質問は具体的であることが望ましく、より良い質問の作法は以下の URL にまとめられていますので、まずは一読することをお勧めします。
https://teratail.com/help/question-tips

[BeatStar]

答えではなくヒントのヒントでもいいのなら質問本文を編集してください。今のままだと丸投げにしか見えません。質問は編集できるので編集しましょう。

[episteme]

あらら、C++じゃないのか...なら僕の回答はスルーしてください。

[thkana]

課題を課せられるということはそれまでの授業を受けているはずで「全くのプログラミング初心者」のはずはない、と思うのですがいかがですか?

Answer 1

残念ながら、ここではコードの作成依頼は受け付けていません

まずはあなたなりにコードを書いてみましょう。その上でわからないことを聞いていただければお答えできるかと思います。

Answer 2

コレ↓を提出したら解説を求められるだろうからうまく答えてね。

#include <iostream>
#include <string>
#include <algorithm>
#include <cctype>

int main() {
  std::string str =
R"_(You can sit before the desk (or in front of the desk). The professor can sit on
the desk (when he's being informal) or behind the desk, and then his feet are
under the desk or beneath the desk. He can stand beside the desk (meaning next
to the desk), before the desk, between the desk and you, or even on the desk (if
he's really strange). If he's clumsy, he can bump into the desk or try to walk
through the desk (and stuff would fall off the desk). Passing his hands over the
desk or resting his elbows upon the desk, he often looks across the desk and
speaks of the desk or concerning the desk as if there were nothing else like the
desk. Because he thinks of nothing except the desk, sometimes you wonder about
the desk, what's in the desk, what he paid for the desk, and if he could live
without the desk. You can walk toward the desk, to the desk, around the desk, by
the desk, and even past the desk while he sits at the desk or leans against the
desk.)_";

  // alphabet(a-z, A-Z) を勘定する
  std::cout << std::count_if(str.begin(), str.end(), [](char ch) { return std::isalpha(ch);}) << std::endl;
}

[追記] C版

#include <stdio.h>
#include <ctype.h>

int main() {
  const char* str =
"You can sit before the desk (or in front of the desk). The professor can sit on "
"the desk (when he's being informal) or behind the desk, and then his feet are "
"under the desk or beneath the desk. He can stand beside the desk (meaning next "
"to the desk), before the desk, between the desk and you, or even on the desk (if "
"he's really strange). If he's clumsy, he can bump into the desk or try to walk "
"through the desk (and stuff would fall off the desk). Passing his hands over the "
"desk or resting his elbows upon the desk, he often looks across the desk and "
"speaks of the desk or concerning the desk as if there were nothing else like the "
"desk. Because he thinks of nothing except the desk, sometimes you wonder about "
"the desk, what's in the desk, what he paid for the desk, and if he could live "
"without the desk. You can walk toward the desk, to the desk, around the desk, by "
"the desk, and even past the desk while he sits at the desk or leans against the "
"desk.";

  int count = 0;
  while ( *str ) if ( isalpha(*str++) ) ++count; 
  printf("%d alphabets.\n", count);
  return 0;
}