Exercises

← Module home · Answers to selected exercises

Graded: ★ routine · ★★ needs thought · ★★★ stretches. Code every ★ and ★★ before peeking at any answer — the try-first rule. Save files as eNN_description.cpp in your exercises folder (naming convention).

E1–E6 · Output basics ★

E1. Print your name, then your city, on two lines — using a single cout statement and '\n'. Then print the same thing using three cout statements, where only the last ends a line.

E2. Print exactly this shape (no trailing spaces):

*
**
***

E3. int apples = 12; double price = 15.5; — print 12 apples cost 186 rupees using one chained statement that computes the 186 rather than typing it.

E4. Print the words tab, sep, end separated by tab characters ('\t'), then print them separated by ` | ` — two lines total.

E5. Predict-then-verify: write a program that prints A, then std::endl, then B, then "\n", then C, then '\n' — as six separate << items. Your prediction first, compiler second.

E6. Print a 3-line “business card”: name, one-line role, and a fun-fact line, with a ===== border line above and below (use whatever border length you like — but keep it consistent).

E7–E12 · Formatting ★★

E7. Print 7 and 1234 right-aligned in a column of width 6, then left-aligned in width 6 — four lines total, pads visible in your prediction.

E8. double unit = 2.5; int qty = 6; — print a receipt line: 6 x 2.50 = 15.00, where both money figures always show two decimals.

E9. Print the header Item Qty Price as three columns of width 8 (left, right, right), then one data row Chai, 3, 90 beneath it.

E10. Using setfill('.'), print Subtotal left-aligned in width 16 and 450 right-aligned in width 8, so the gap fills with dots: Subtotal........450.

E11. Show the difference between default and fixed formatting of double x = 2.0/3.0; — print x twice: once before any manipulator, once with fixed << setprecision(4).

E12. A marks table: print three students (name width 12 left; marks width 5 right) with names Ayesha, Bilal, Chen and marks 88, 61, 95. Header row included; columns must line up.

E13–E18 · Input basics ★★

E13. Ask for a whole number and print its square and its cube, e.g. input 5 → square 25, cube 125. Prompts on their own line, answers formatted as shown.

E14. Ask for two whole numbers and print their sum, difference, and product on one line each — labels padded to width 10 with dots (Sum.......18).

E15. Ask for width and height in one prompt; user may type 12 9 or 12⏎9. Print Area: 108 either way. Then explain (comment in the code) why both input styles work.

E16. Ask for a temperature and a unit letter (C or F); echo them back exactly: Reading: 37.5 C. (No conversion yet — Lab 3 owns that.)

E17. Ask for an item name (one word) and a price; print 3 x chai @ 40 = 120 style output for quantity 3. Name may contain no spaces — say that constraint in your prompt.

E18. Copy the validation-loop pattern from Lesson 2 §2.5 into a program that asks for a positive even number: reject non-numbers by failure, reject odd numbers by… try it and see what happens without an if inside the loop, then read the pattern again and fix it.

E19–E24 · Lines and getline ★★–★★★

E19. Read one whole line (a poem title with spaces) and print it in quotes with its length: "The Rime of the Ancient Mariner" (31 chars).

E20. Fix the trap: ask for an age (>>), then a full name. Your first version must contain the bug on purpose (print what the name variable holds to prove it), your second version must cure it with cin.ignore(1000, '\n'), your third with getline(std::cin >> ws, name). Three files, three comments explaining the difference.

E21. Read an address in three lines (house/street, city, country) with three getlines; print them as house | city | country on one line.

E22. Read a one-word username (>>) and then a full display name (getline, cured); print [username] displays as [display name].

E23. ★★★ Read a full line, then print its first word, a separator, and the rest of the line. (You may use line.find(' ') and line.substr(...) — look them up, they are standard string tools, or solve it with two reads: a word then a line.)

E24. ★★★ A two-item form: item name (may contain spaces), then quantity. Input arrives name-first (Chai 250ml⏎3⏎). Print the order line. Which reader gets which field, and what must you cure?

Answers to selected exercises

std::cout << "Nadeem\nLahore\n";

std::cout << "Nadeem\n";
std::cout << "Lahore";
std::cout << "\n";

std::cout << apples << " apples cost " << apples * price << " rupees\n";

#include <iostream>
#include <iomanip>

int main() {
    double unit = 2.5;
    int qty = 6;
    std::cout << qty << " x " << std::fixed << std::setprecision(2)
              << unit << " = " << qty * unit << "\n";
    return 0;
}

#include <iostream>

int main() {
    int n;
    std::cout << "Whole number: " << std::endl;
    std::cin >> n;
    std::cout << "square " << n * n << ", cube " << n * n * n << "\n";
    return 0;
}

std::cin >> age;
std::getline(std::cin, name);          // reads the leftover '\n' -> ""

std::cin >> age;
std::cin.ignore(1000, '\n');           // discard remainder of the line
std::getline(std::cin, name);          // now reads the real name line

std::cin >> age;
std::getline(std::cin >> ws, name);    // skip leading ws, then read line

← Module home · Debugging hunts →