Toma de decisiones en C/C++ (if, if..else, Nested if, if-else-if)

Hay situaciones en la vida real en las que necesitamos tomar algunas decisiones y, en base a estas decisiones, decidimos qué debemos hacer a continuación. También surgen situaciones similares en la programación en las que necesitamos tomar algunas decisiones y, en base a estas decisiones, ejecutaremos el siguiente bloque de código. Por ejemplo, en C, si ocurre x, ejecute y, de lo contrario, ejecute z. También puede haber múltiples condiciones como en C si ocurre x, luego ejecute p, de lo contrario, si ocurre la condición y, ejecute q, de lo contrario, ejecute r. Esta condición de C else-if es una de las muchas formas de importar múltiples condiciones. 
 

// C program to illustrate If statement
#include <stdio.h>
 
int main() {
    int i = 10;
 
    if (i > 15)
    {
       printf("10 is less than 15");
    }   
    
    printf("I am Not in if");
}

// C++ program to illustrate If statement
#include<iostream>
using namespace std;
 
    int main()
    {
        int i = 10;
  
        if (i > 15)
        {
           cout<<"10 is less than 15";
        }   
        
        cout<<"I am Not in if";
    }

// C program to illustrate If statement
#include <stdio.h>
 
int main() {
    int i = 20;
 
    if (i < 15){
       
        printf("i is smaller than 15");
    }
    else{
       
        printf("i is greater than 15");
    }       
    return 0;   
}

// C++ program to illustrate if-else statement
#include<iostream>
using namespace std;
 
int main()
 {
        int i = 20;
  
        if (i < 15)
            cout<<"i is smaller than 15";
        else
            cout<<"i is greater than 15";
             
    return 0;   
 }

// C program to illustrate nested-if statement
#include <stdio.h>
 
int main() {
    int i = 10;
 
    if (i == 10)
    {
        // First if statement
        if (i < 15)
           printf("i is smaller than 15\n");
 
        // Nested - if statement
        // Will only be executed if statement above
        // is true
        if (i < 12)
            printf("i is smaller than 12 too\n");
        else
            printf("i is greater than 15");
    }
 
    return 0;
}

// C++ program to illustrate nested-if statement
#include <iostream>
using namespace std;
 
int main()
{
    int i = 10;
 
    if (i == 10)
    {
        // First if statement
        if (i < 15)
           cout<<"i is smaller than 15\n";
 
        // Nested - if statement
        // Will only be executed if statement above
        // is true
        if (i < 12)
            cout<<"i is smaller than 12 too\n";
        else
            cout<<"i is greater than 15";
    }
 
    return 0;
}

// C program to illustrate nested-if statement
#include <stdio.h>
 
int main() {
    int i = 20;
  
    if (i == 10)
        printf("i is 10");
    else if (i == 15)
        printf("i is 15");
    else if (i == 20)
        printf("i is 20");
    else
        printf("i is not present");
}

// C++ program to illustrate if-else-if ladder
#include<iostream>
using namespace std;
 
int main()
{
    int i = 20;
  
    if (i == 10)
        cout<<"i is 10";
    else if (i == 15)
        cout<<"i is 15";
    else if (i == 20)
        cout<<"i is 20";
    else
        cout<<"i is not present";
}

// C program to illustrate
// Linear Search
 
#include <stdio.h>
 
void findElement(int arr[], int size, int key)
{
    // loop to traverse array and search for key
    for (int i = 0; i < size; i++) {
        if (arr[i] == key) {
            printf("Element found at position: %d", (i + 1));
            break;
        }
    }
}
 
int main() {
    int arr[] = { 1, 2, 3, 4, 5, 6 };
     
    // no of elements
    int n = 6; 
     
    // key to be searched
    int key = 3;
 
    // Calling function to find the key
    findElement(arr, n, key);
 
    return 0;
}

// CPP program to illustrate
// Linear Search
#include <iostream>
using namespace std;
 
void findElement(int arr[], int size, int key)
{
    // loop to traverse array and search for key
    for (int i = 0; i < size; i++) {
        if (arr[i] == key) {
            cout << "Element found at position: " << (i + 1);
            break;
        }
    }
}
 
// Driver program to test above function
int main()
{
    int arr[] = { 1, 2, 3, 4, 5, 6 };
    int n = 6; // no of elements
    int key = 3; // key to be searched
 
    // Calling function to find the key
    findElement(arr, n, key);
 
    return 0;
}

// C program to explain the use
// of continue statement
#include <stdio.h>
 
int main() {
    // loop from 1 to 10
    for (int i = 1; i <= 10; i++) {
 
        // If i is equals to 6,
        // continue to next iteration
        // without printing
        if (i == 6)
            continue;
 
        else
            // otherwise print the value of i
            printf("%d ", i);
    }
 
    return 0;
}

// C++ program to explain the use
// of continue statement
 
#include <iostream>
using namespace std;
 
int main()
{
    // loop from 1 to 10
    for (int i = 1; i <= 10; i++) {
 
        // If i is equals to 6,
        // continue to next iteration
        // without printing
        if (i == 6)
            continue;
 
        else
            // otherwise print the value of i
            cout << i << " ";
    }
 
    return 0;
}

#include<iostream>
using namespace std;
 
int main(){
    int gfg=0; // local variable for main
    cout<<"Before if-else block "<<gfg<<endl;
    if(1){
        int gfg = 100; // new local variable of if block
        cout<<"if block "<<gfg<<endl;
    }
    cout<<"After if block "<<gfg<<endl;
    return 0;
}
/*
    Before if-else block 0
    if block 100
    After if block 0
*/

#include <stdio.h>
 
int main() {
 
      int gfg=0; // local variable for main
    printf("Before if-else block %d\n",gfg);
    if(1){
        int gfg = 100; // new local variable of if block
        printf("if block %d\n",gfg);
    }
    printf("After if block %d",gfg);
  return 0;
}

// C program to print numbers
// from 1 to 10 using goto statement
#include <stdio.h>
 
// function to print numbers from 1 to 10
void printNumbers()
{
    int n = 1;
label:
    printf("%d ",n);
    n++;
    if (n <= 10)
        goto label;
}
 
// Driver program to test above function
int main() {
    printNumbers();
    return 0;
}

// C++ program to print numbers
// from 1 to 10 using goto statement
#include <iostream>
using namespace std;
 
// function to print numbers from 1 to 10
void printNumbers()
{
    int n = 1;
label:
    cout << n << " ";
    n++;
    if (n <= 10)
        goto label;
}
 
// Driver program to test above function
int main()
{
    printNumbers();
    return 0;
}

// C code to illustrate return
// statement
#include <stdio.h>
 
// non-void return type
// function to calculate sum
int SUM(int a, int b)
{
    int s1 = a + b;
    return s1;
}
 
// returns void
// function to print
void Print(int s2)
{
    printf("The sum is %d", s2);
    return;
}
 
int main()
{
    int num1 = 10;
    int num2 = 10;
    int sum_of = SUM(num1, num2);
    Print(sum_of);
    return 0;
}

// C++ code to illustrate return
// statement
#include <iostream>
using namespace std;
 
// non-void return type
// function to calculate sum
int SUM(int a, int b)
{
    int s1 = a + b;
    return s1;
}
 
// returns void
// function to print
void Print(int s2)
{
    cout << "The sum is "<< s2;
    return;
}
 
int main()
{
    int num1 = 10;
    int num2 = 10;
    int sum_of = SUM(num1, num2);
    Print(sum_of);
    return 0;
}