Grafit

This program collects monthly sales figures for 12 months, storing three-character month abbreviations in a string array and numeric values in a numeric array, then renders a horizontal bar chart on screen. Each bar is drawn using CHR$ 128 (a block graphic separator) followed by repeated CHR$ 134 characters (a solid block graphic) scaled so the highest value fills 22 columns. After the chart, total and average sales figures are printed. The SCROLL calls during input keep the display tidy on the 32-column screen, and the fractional STEP (B/22) in the FOR loop controls bar length proportionally to the peak value.

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Program Analysis

Program Structure

The program is divided into two clear phases. Lines 9000–9160 handle data entry: two parallel arrays (A$(12,3) for month names and A(12) for sales values) are populated via INPUT, with the peak value tracked in B. Lines 9170–9270 render the bar chart and summary. Line 9997 stops execution; line 9998 saves the program; line 9999 loops back to redraw — allowing the chart to be redrawn without re-entering data.

Array Design

DIM A$(12,3) declares a 12-element string array where each element is exactly 3 characters, enforcing the “first 3 characters” prompt. DIM A(12) holds the corresponding numeric sales figures. The parallel-array approach is idiomatic for this dialect, which lacks record or struct types.

Bar Chart Rendering

Each bar is drawn on a single PRINT line. The month name and value are printed left-aligned, then TAB 9 positions the cursor before the bar. CHR$ 128 (block graphic ▝ or similar solid block, used as a visual separator) precedes the bar body. The bar itself consists of repeated CHR$ 134 characters printed by the inner FOR C loop.

Scaling Technique

Bar length is controlled by iterating FOR C=.01 TO A(N) STEP B/22. Dividing the peak value B by 22 sets the step size so the largest bar prints exactly 22 block characters, while all others are proportionally shorter. Starting at .01 rather than 0 or 1 means the loop always executes at least once for any positive sales value, ensuring every month gets at least one character.

Display Management

Four SCROLL calls (lines 9050, 9090, 9130, 9140) during data entry scroll the display upward before and after each prompt/response pair, keeping the screen uncluttered during the 12-iteration input loop. CLS at line 9170 clears the screen before chart rendering.

Summary Output

Lines 9260–9270 print total and average sales below the chart. The comma separators in PRINT ,,,,"TOTAL SALES = $";T advance the print position by four tab columns, indenting the summary to approximate centre-screen alignment on a 32-column display.

Notable Anomalies

• LET T=0 appears at both line 9020 and line 9175. The accumulator is reset a second time just before the chart loop, which is redundant but harmless; it may reflect an edit where the chart loop was intended to be re-enterable from 9999 without re-accumulating.
• If any sales value is zero, B remains zero after all entries and STEP B/22 becomes STEP 0, which would cause an infinite loop. The program assumes at least one non-zero entry.
• B is initialised to 0 but never reset before the chart phase; if GOTO 9999 is reached after a prior run with different data, B correctly retains the peak from the most recent input session.

Line Reference Summary

Lines	Purpose
9000–9030	Array and variable initialisation
9040–9160	12-month data entry loop, peak tracking
9170–9175	Screen clear, accumulator reset
9180–9250	Bar chart rendering loop
9260–9270	Total and average summary
9997	STOP
9998	SAVE program
9999	Redraw loop entry point