Laboratory: Stings in C

Summary: In this laboratory, you will experiment with C's strings and the various standard string procedures.

Contents:

• Exercises
  • Exercise 0: Preparation
  • Exercise 01: Printing Strings
  • Exercise 2: Declaring Strings
  • Exercise 03: Uninitialized Strings
  • Exercise 4: Assigning Strings
  • Exercise 5: Concatenating Strings
  • Exercise 6: Reversing Strings
  • Exercise 7: The Name Game

Exercises

Exercise 0: Preparation

Create a new directory for this laboratory.

Exercise 01: Printing Strings

Consider the following two mechanisms for printing the string antelope.

a. Which do you prefer? Why?

• printf(antelope);
• printf("%s", antelope);

b. Write a simple program in which the two statements have different output.

Exercise 2: Declaring Strings

Here are a number of different string declarations.

  char *baboon;
  char *chimpanzee = "animal";
  char dolphin[];
  char emu[] = "animal";
  char fox[8];
  char fox[8] = "animal";

a. Which are valid and which are invalid?

b. How do the valid declarations differ?

Exercise 03: Uninitialized Strings

a. Consider the following declaration and code

  char gorilla[8];
  char ch;
  ...
  printf("sizeof(gorilla): %d\n", sizeof(gorilla));
  printf("strlen(gorilla): %d\n", strlen(gorilla));
  printf("gorilla: '%s'\n", gorilla);

What do you expecct the output to be?

b. How would your answer change if gorilla were declared with

  char *gorilla;

c. Verify your hypotheses experimentally.

d. What do your results suggest?

Exercise 4: Assigning Strings

Suppose hippo and iguana are both declared as strings. When, if ever, is

  iguana = hippo;

a valid assignment?

Note that you may need to try different kinds of declarations.

Exercise 5: Concatenating Strings

Consider the folling declarations:

  char jackal[8] = "animal";
  char koala[8] = "animal";
  char lemur[8] = "animal";

a. What do you expect the effect of the following instruction to be?

  strcat(koala,"istic");

b. Verify your answer experimentally. Make sure to print out all three strings.

c. Explain your answer.

d. Assume you didn't execute the instruction from step a. What do you expect the effect of the following instruction to be?

  strncat(koala, "ed");

e. Verify your answer experimentally. Make sure to print out all three strings.

f. Explain your answer.

Exercise 6: Reversing Strings

Write a procedure, char *reverse(char *str), that reverses the order of characters in str and returns the modified str. Your procedure should modify str.

Exercise 7: The Name Game

Write a program that implements the Name Game.