C++ if-else Yapısı Nedir?
C++ programlama dilinde if-else yapısı, koşullu ifadelerin kontrol edilmesi için kullanılır. Bir programda belirli bir şartın doğru (true) veya yanlış (false) olmasına göre farklı işlemler yapılmasını sağlar. Örneğin; bir sayının pozitif mi, negatif mi olduğunu kontrol etmek, kullanıcının girdiği şifrenin doğru olup olmadığını doğrulamak ya da öğrencinin notuna göre harf karşılığını göstermek için if-else kullanılır.
C++ if-else Kullanım Avantajları
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Program akışını şartlara göre yönlendirme imkânı sağlar.
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Daha dinamik ve kullanıcı odaklı uygulamalar geliştirmeye yardımcı olur.
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Matematiksel, mantıksal ve metinsel karşılaştırmalarda yaygın olarak kullanılır.
C++ if-else Örnek Kullanım
if (sayi % 2 == 0) {
cout << "Sayi cifttir.";
} else {
cout << "Sayi tektir.";
}Bu örnekte, girilen sayının tek mi çift mi olduğu kontrol edilerek kullanıcıya doğru sonuç gösterilir.
1. Sayının Pozitif veya Negatif Olduğunu Bulma
#include <iostream>
using namespace std;int sayi;
cout << “Bir sayi giriniz: “;
cin >> sayi;
cout << “Sayi pozitif veya sifirdir.” << endl;
} else {
cout << “Sayi negatiftir.” << endl;
}
return 0;
}
3. Yaş Kontrolü (18 yaş üstü mü?)
#include <iostream>
using namespace std;int main() {
int yas;
cout << "Yasinizi giriniz: ";
cin >> yas;if (yas >= 18) {
cout << "Ehliyet alabilirsiniz." << endl;
} else {
cout << "Ehliyet almak icin yasiniz yeterli degil." << endl;
}
return 0;
}
4. Not Harf Dönüşümü
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<pre class="overflow-y-auto p-4" dir="ltr"><code class="whitespace-pre! language-cpp"><code class="whitespace-pre! language-cpp"><span class="hljs-meta">#<span class="hljs-keyword">include</span></span> <span class="hljs-string"><iostream></span>
<span class="hljs-keyword">using</span> <span class="hljs-keyword">namespace</span> std;</code></code><span class="hljs-function"><span class="hljs-type">int</span></span> <span class="hljs-title">main</span><span class="hljs-params">()</span> {
<span class="hljs-type">int</span> notu;
cout << <span class="hljs-string">"Notunuzu giriniz (0-100): "</span>;
cin >> notu;<code class="whitespace-pre! language-cpp"><code class="whitespace-pre! language-cpp"></code></code><span class="hljs-keyword">if</span> (notu >= <span class="hljs-number">85</span>) {
cout << <span class="hljs-string">"AA"</span> << endl;
} <span class="hljs-keyword">else</span> <span class="hljs-keyword">if</span> (notu >= <span class="hljs-number">70</span>) {
cout << <span class="hljs-string">"BB"</span> << endl;
} <span class="hljs-keyword">else</span> <span class="hljs-keyword">if</span> (notu >= <span class="hljs-number">50</span>) {
cout << <span class="hljs-string">"CC"</span> << endl;
} <span class="hljs-keyword">else</span> {
cout << <span class="hljs-string">"FF (Kaldiniz)"</span> << endl;
}
<span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}
5. En Büyük Sayıyı Bulma (2 sayı)
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<pre class="overflow-y-auto p-4" dir="ltr"><code class="whitespace-pre! language-cpp"><code class="whitespace-pre! language-cpp"><span class="hljs-meta">#<span class="hljs-keyword">include</span></span> <span class="hljs-string"><iostream></span>
<span class="hljs-keyword">using</span> <span class="hljs-keyword">namespace</span> std;</code></code><span class="hljs-function"><span class="hljs-type">int</span></span> <span class="hljs-title">main</span><span class="hljs-params">()</span> {
<span class="hljs-type">int</span> a, b;
cout << <span class="hljs-string">"Iki sayi giriniz: "</span>;
cin >> a >> b;<code class="whitespace-pre! language-cpp"><code class="whitespace-pre! language-cpp"></code></code><span class="hljs-keyword">if</span> (a > b) {
cout << <span class="hljs-string">"En buyuk sayi: "</span> << a << endl;
} <span class="hljs-keyword">else</span> {
cout << <span class="hljs-string">"En buyuk sayi: "</span> << b << endl;
}
<span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}
6. Kullanıcı Şifre Kontrolü
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<pre class="overflow-y-auto p-4" dir="ltr"><code class="whitespace-pre! language-cpp"><code class="whitespace-pre! language-cpp"><span class="hljs-meta">#<span class="hljs-keyword">include</span></span> <span class="hljs-string"><iostream></span>
<span class="hljs-keyword">using</span> <span class="hljs-keyword">namespace</span> std;</code></code><span class="hljs-function"><span class="hljs-type">int</span></span> <span class="hljs-title">main</span><span class="hljs-params">()</span> {
string sifre;
cout << <span class="hljs-string">"Sifreyi giriniz: "</span>;
cin >> sifre;<code class="whitespace-pre! language-cpp"><code class="whitespace-pre! language-cpp"></code></code><span class="hljs-keyword">if</span> (sifre == <span class="hljs-string">"12345"</span>) {
cout << <span class="hljs-string">"Giris basarili."</span> << endl;
} <span class="hljs-keyword">else</span> {
cout << <span class="hljs-string">"Yanlis sifre!"</span> << endl;
}
<span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}
7. Harf Kontrolü (Sesli mi Sessiz mi?)
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<pre class="overflow-y-auto p-4" dir="ltr"><code class="whitespace-pre! language-cpp"><code class="whitespace-pre! language-cpp"><span class="hljs-meta">#<span class="hljs-keyword">include</span></span> <span class="hljs-string"><iostream></span>
<span class="hljs-keyword">using</span> <span class="hljs-keyword">namespace</span> std;</code></code><span class="hljs-function"><span class="hljs-type">int</span></span> <span class="hljs-title">main</span><span class="hljs-params">()</span> {
<span class="hljs-type">char</span> harf;
cout << <span class="hljs-string">"Bir harf giriniz: "</span>;
cin >> harf;<code class="whitespace-pre! language-cpp"><code class="whitespace-pre! language-cpp"></code></code><span class="hljs-keyword">if</span> (harf==<span class="hljs-string">'a'</span> || harf==<span class="hljs-string">'e'</span> || harf==<span class="hljs-string">'i'</span> || harf==<span class="hljs-string">'o'</span> || harf==<span class="hljs-string">'u'</span>) {
cout << <span class="hljs-string">"Sesli harf."</span> << endl;
} <span class="hljs-keyword">else</span> {
cout << <span class="hljs-string">"Sessiz harf."</span> << endl;
}
<span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}
8. Üç Sayının En Büyüğünü Bulma
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<pre class="overflow-y-auto p-4" dir="ltr"><code class="whitespace-pre! language-cpp"><code class="whitespace-pre! language-cpp"><span class="hljs-meta">#<span class="hljs-keyword">include</span></span> <span class="hljs-string"><iostream></span>
<span class="hljs-keyword">using</span> <span class="hljs-keyword">namespace</span> std;</code></code><span class="hljs-function"><span class="hljs-type">int</span></span> <span class="hljs-title">main</span><span class="hljs-params">()</span> {
<span class="hljs-type">int</span> a, b, c;
cout << <span class="hljs-string">"Uc sayi giriniz: "</span>;
cin >> a >> b >> c;<code class="whitespace-pre! language-cpp"><code class="whitespace-pre! language-cpp"></code></code><span class="hljs-keyword">if</span> (a >= b && a >= c) {
cout << <span class="hljs-string">"En buyuk: "</span> << a << endl;
} <span class="hljs-keyword">else</span> <span class="hljs-keyword">if</span> (b >= a && b >= c) {
cout << <span class="hljs-string">"En buyuk: "</span> << b << endl;
} <span class="hljs-keyword">else</span> {
cout << <span class="hljs-string">"En buyuk: "</span> << c << endl;
}
<span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}
9. Maaş Zammı Hesaplama
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<pre class="overflow-y-auto p-4" dir="ltr"><code class="whitespace-pre! language-cpp"><code class="whitespace-pre! language-cpp"><span class="hljs-meta">#<span class="hljs-keyword">include</span></span> <span class="hljs-string"><iostream></span>
<span class="hljs-keyword">using</span> <span class="hljs-keyword">namespace</span> std;</code></code><span class="hljs-function"><span class="hljs-type">int</span></span> <span class="hljs-title">main</span><span class="hljs-params">()</span> {
<span class="hljs-type">int</span> maas;
cout << <span class="hljs-string">"Maasinizi giriniz: "</span>;
cin >> maas;<code class="whitespace-pre! language-cpp"><code class="whitespace-pre! language-cpp"></code></code><span class="hljs-keyword">if</span> (maas < <span class="hljs-number">5000</span>) {
maas += maas * <span class="hljs-number">0.20</span>; <span class="hljs-comment">// %20 zam</span>
} <span class="hljs-keyword">else</span> {
maas += maas * <span class="hljs-number">0.10</span>; <span class="hljs-comment">// %10 zam</span>
}
cout << <span class="hljs-string">"Yeni maas: "</span> << maas << endl;
<span class="hljs-keyword">return</span> <span class="hljs-number">0</span>;
}
10. Basit Hesap Makinesi
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<pre class="overflow-y-auto p-4" dir="ltr"><code>
#include
using namespace std;int main() {
int a, b;
char islem;
cout << "Iki sayi giriniz: "; cin >> a >> b;
cout << "Islem seciniz (+, -, *, /): "; cin >> islem;if (islem == '+') {
cout << "Sonuc: " << a + b << endl;
} else if (islem == '-') {
cout << "Sonuc: " << a - b << endl;
} else if (islem == '*') {
cout << "Sonuc: " << a * b << endl;
} else if (islem == '/') {
if (b != 0)
cout << "Sonuc: " << a / b << endl;
else
cout << "Hata: Sifira bolme!" << endl;
} else {
cout << "Gecersiz islem!" << endl;
}
return 0;
}
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