A practical introduction to Pascal programming language - GIARA

More documents

Recommendations

Info

Data structuresExercise 4.22. Create a program that reads a string and draws it as a left-based pyramid. Forexample, the word computer must look like:croemtpu□This program consists of writing, at line i, the i-th char of the string preceded by a givennumber of blank spaces. The key is being able to summarize such number in a single formula, sothat the program becomes readable. In this case, such formula is min(i-1,length(str)-1. Notethat by finding out the expression we avoid using extra alternative constructions to discriminatebetween the first and the last half of the string.Program 103: Exercise 4.22program c04e22;uses math;constN=15;varstr:STRING[N];i,j:integer;begin(* Reading the text *)write(’Please input the string of, at most, ’,N,’ chars: ’);readln(str);(* Writing the matrix *)for i:=1 to length(str) dobeginfor j:=1 to min(i-1,length(str)-i) dowrite(’ ’);writeln(str[i])endend.⊡Exercise 4.23. Create a program that reads a string and draws it as an upside down pyramid.For example, the word computer must look like:computer□In order to display this structure we have to realize that, between each pair of chars, we needto put blank spaces. Hence, again it becomes a problem of epitomizing the number of blankspaces depending upon the number of the row we are in. First, we have to decide how manyblank spaces must be written before the first char, and then how many before the second. On87
A Practical Introduction to Pascal Programming Languagethe leftmost part of the i-th line we have to include as many as i − 1 blank spaces. Then, afterthe first char we have to write as many black spaces as the length of the line minus 2 (the spaceoccupied by the chars) and 2 · (i − 1) (the number of blanks paces on the left and right of suchchars). Hence, for a line i we need length(str) − 2 ∗ i blank spaces.Program 104: Exercise 4.23program c04e23;uses math;constN=15;varstr:STRING[N];i,j:integer;begin(* Reading the string *)write(’Please input the string of, at most, ’,N,’ chars: ’);readln(str);(* Writing the matrix *)for i:=1 to ceil(length(str)/2) dobeginfor j:=1 to min(i-1,length(str)-i) dowrite(’ ’);write(str[i]);for j:=1 to length(str)-(2*i) dowrite(’ ’);if (abs( (i-1)-(length(str)-i))-1)>=0 thenwriteln(str[length(str)-i+1])elsewritelnendend.⊡Exercise 4.24. Create a program that reads a string and draws it as a bottom-based pyramid.For example, the word computer must look like:computer□We can understand this problem as a derivation of the preceding one. Indeed, we can achievethe solution by tweaking the value of the variable used in the outer for iterative construction,and changing the to clause by downto.Program 105: Exercise 4.24program c04e24;uses math;constN=15;varstr:STRING[N];i,j:integer;begin(* Reading the string *)88
Page 4:
A Practical Introduction to Pascal
Page 8:
ContentsIntroduction to this book 9
Page 11 and 12:
Guidelines and structureThis book i
Page 13 and 14:
Page 15 and 16:
Page 17 and 18:
Page 19 and 20:
Page 21 and 22:
Page 23 and 24:
Page 25 and 26:
Page 27 and 28:
Page 29 and 30:
Page 31 and 32:
Page 33 and 34:
Page 35 and 36:
Page 37 and 38: A Practical Introduction to Pascal
Page 87: A Practical Introduction to Pascal
Page 91: A Practical Introduction to Pascal
show all

A practical introduction to Pascal programming language - GIARA

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?