Lab 12

1
Lab 12

• Strings
• Recursion
• Note
• Read the whole Chapter 9 and 10.

2
Review of Strings

• Strings in C are arrays of characters ended by
  the null character \0.
• String input is done using scanf with s
  descriptor for strings seperated by whitespace,
  usings gets for input of whole lines, and using
  getchar for single character input.
• String output is done using printf with s
  descriptor putchar does single character output.
• includeltstdio.hgt
• void main()
• char first_name20,last_name20,city25
• printf("Enter the city name")
• gets(city)
• printf("Enter your last and first name ")
• scanf("s s",first_name,last_name)
• printf("Hi s s, you live in ",first_name,last_na
  me)
• puts(city)

3

• //using getchar() and putchar
• includeltstdio.hgt
• void main()
• char c
• printf("Enter a character")
• c getchar()
• putchar(c)
• //using strcat
• includeltstdio.hgt
• include ltstring.hgt
• void main(void)
• char ch115"hello"
• char ch2" Sir"
• printf("Before s\n" ,ch1)
• strcat(ch1,ch2)
• printf("After s\n" ,ch1)

4

• //using strncat
• includeltstdio.hgt
• include ltstring.hgt
• void main(void)
• char ch115"hello"
• char ch2" Sir"
• printf("Before s\n" ,ch1)
• strncat(ch1,ch2,2)
• printf("After s\n" ,ch1)
• //using strlen()
• includeltstdio.hgt
• include ltstring.hgt
• void main(void)
• char ch115"hello"
• char ch2" Sir"
• printf("Before s\n" ,ch1)
• strncat(ch1,ch2,2)
• printf("After s, ch1 size d \n"
  ,ch1,strlen(ch1))

5

• //using strcmp
• includeltstdio.hgt
• include ltstring.hgt
• void main(void)
• char ch115"Amal"
• char ch2"Yasmine"
• int result
• resultstrcmp(ch1,ch2)
• if(result gt0)
• printf("ch1 after ch2 \n")
• else if(result lt0)
• printf("ch1 before ch2 \n")
• else
• printf("the 2 strings are equal \n")

6

• Exercise1
• use strncmp(string1,string2,lgmax)
• use strnicmp(string1,string2,lgmax)
• includeltstdio.hgt
• include ltstring.hgt
• void main(void)
• char ch115"AM"
• char ch2"am"
• int result
• resultstricmp(ch1,ch2)
• if(result gt0)
• printf("ch1 after ch2 \n")
• else if(result lt0)
• printf("ch1 before ch2 \n")
• else
• printf("the 2 strings are equal \n")

7

• //use of strncpy
• includeltstdio.hgt
• include ltstring.hgt
• void main(void)
• char ch115"AAAAAAAAAAAAA"
• char ch2"BBBBB"
• strncpy(ch1,ch2,5)
• printf("ch1s\n",ch1)
• //use of atoi
• includeltstdio.hgt
• include ltstdlib.hgt
• void main(void)
• char ch115"143"
• printf("positiond\n",atoi(ch1))

8

• //use of atof()
• includeltstdio.hgt
• include ltstdlib.hgt
• void main(void)
• char ch115"143.4"
• printf("position.2f\n",atof(ch1))
• //use of strchr
• includeltstdio.hgt
• include ltstring.hgt
• efine CAR 'e'
• define LGMAX 132
• void main(void)
• char ch1LGMAX1
• char adr
• int ncar
• printf("Enter a string ")
• gets(ch1)
• ncar0
• adrch1

9

• Write a C program that deletes all the letters
  e in a string and displays the new string (use
  strchr() and strcpy()).
• Write a C program taht reads a string and
  displays it in reverse order.
• (use strlen() and putchar()).
• Recursion
• includeltstdio.hgt
• long facto(int n)
• long result
• if(ngt1)
• resultfacto(n-1)n
• else
• result1
• return result
• void main(void)
• int n
• printf("enter n ")
• scanf("d",n)
• printf("Factorial of d is ld \n",n,facto(n))

10

• Write a C program that use a recursive function
  to compute Ackermann function defined as
  following
• A(m,n)A(m-1,A(m,n-1)) for mgt0 and n gt0
• A(0,n)n1 for ngt0
• A(m,0)A(m-1,1) for mgt 0