//1) Write a C function that concatenates two input strings S1 and S2 in string S1.
                #include<stdio.h>
                #include<string.h>

                int main()
                {
                    char str1[40],str2[40] ;
                    printf("enter string1: ");
                    gets(str1);
                    printf("enter string2: ");
                    gets(str2);
                    printf("%s",strcat(str1,str2));
                    return 0;
                }

                //--------------------------------------------------------------------------------------------------

                //2) Write a C program that reads 10 characters from the user, and then searches for the position of
                //the character z.
                #include <stdio.h>
                #include <string.h>

                int main()
                {
                    char a[10];
                    printf("enter 10 characterss : ");
                    scanf("%s",a);

                    for(int i=0 ; i<10 ; i++)
                    {
                        if(a[i]=='z')
                            printf("the position of the character z : %d\n",i+1);
                    }
                }

                //--------------------------------------------------------------------------------------------------

                //3) Write a C program that reads string S1 and certain letter from the user, then call your own
                //function that return the number of occurrences of the given character in the given string.
                #include <stdio.h>
                #include <string.h>

                int find(char s1[] , int sizeofs1 , char c1)
                {
                    int a=0;
                    for(int i=0 ; i< sizeofs1 ; i++)
                    {
                        if(s1[i]==c1)
                            a++;
                    }
                    return a;
                }
                int main()
                {
                    char s1[30];
                    char c1;
                    printf("enter the string : ");
                    gets(s1);
                    printf("enter the letter: ");
                    scanf("%c",&c1);
                    printf("the number of occurrences of the given character in the given string :%d",find(s1,strlen(s1),c1));
                }

                //--------------------------------------------------------------------------------------------------

                //4) Write a C function that take two strings (array of characters) and return one if the 1st is part of
                //the 2nd and zero otherwise
                #include <stdio.h>
                #include <string.h>
                find();
                int main()
                {
                    char s1[30],s2[30];
                    printf("enter string 1 : ");
                    scanf("%s",s1);
                    printf("enter string 2 : ");
                    scanf("%s",s2);
                    if(strlen(s1)>strlen(s2))
                        printf("%d",0);
                    printf("%d",find(s1,strlen(s2),s2));
                }

                int find(char s1[],int size ,char s2[])
                {
                    int counter=0,a=0;
                    while(s1[a]!='\0')
                    {
                        a++;
                    }
                for(int i=0 ; i<a ;i++)
                    {
                        for(int j=0 ; j<size ;j++)
                        {
                            if(s1[i]==s2[j])
                            {
                                counter++;
                                break;
                            }
                        }
                        if(counter==a)
                            break;
                    }
                    if(counter==a)
                        return 1;
                    else
                        return 0;
                }

                //--------------------------------------------------------------------------------------------------

                //5) Write a C code to reverse a string by recursion
                #include <stdio.h>
                #include <string.h>

                char reverse(char s[],int size,int count,int a)
                {
                    while(count!=-1)
                    {
                        if(a==1)
                            break;
                        printf("%c",s[count]);
                        return reverse(s,size,count-1,a+1);
                    }
                    if(a==1)
                        return reverse(s,size,count-1,a+1);
                }

                int main()
                {
                    char s[20];
                    int i=0;
                    printf("enter the string: ");
                    gets(s);
                    while(s[i]!='\0')
                    {
                        i++;
                    }
                    reverse(s,20,i,1);
                }