Task 206: .F4 File Format
Task 206: .F4 File Format
1. List of all the properties of this file format intrinsic to its file system
The .F4 file format is associated with Fortran IV (Fortran 66) source code files. It is a text-based format using a fixed-column structure derived from punch card conventions. Each line is typically 80 characters long, and the format defines specific column ranges for different elements. These properties are intrinsic to the format and are used by Fortran IV compilers to parse the source code. The key properties for each line are:
- Line Type: Determines if the line is a comment or a statement. If column 1 is 'C' or '*', it is a comment; otherwise, it is a statement line.
- Label: Columns 1-5 (numeric label for statements, right-justified with leading blanks if shorter than 5 digits; ignored for comments).
- Continuation Indicator: Column 6 (non-blank character if the line is a continuation of the previous statement; blank otherwise).
- Statement Body: Columns 7-72 (the actual Fortran code or comment text).
- Identification/Sequence Number: Columns 73-80 (optional field for sequence numbers or identification; often ignored by compilers but part of the format).
Lines longer or shorter than 80 characters may be padded or truncated, but the format assumes fixed-width parsing. Encoding is typically ASCII.
2. Two direct download links for files of format .F4
Note: .F4 files are rare in modern usage, as Fortran source is more commonly saved with .f or .for extensions. However, the following are sample Fortran IV-compatible source code files in fixed format from a reliable academic source (Florida State University). They can be renamed to .F4 if needed:
- https://people.sc.fsu.edu/~jburkardt/f77_src/asa047/asa047.f
- https://people.sc.fsu.edu/~jburkardt/f77_src/asa058/asa058.f
3. Ghost blog embedded HTML JavaScript for drag and drop .F4 file dump
Below is the complete HTML code with embedded JavaScript that can be pasted into a Ghost blog post (using the HTML card/block). It creates a drag-and-drop area where a user can drop a .F4 file. The script reads the file as text, parses each line according to the .F4 properties, and dumps them to the screen in a readable format.
Drag and drop a .F4 file here
4. Python class for .F4 files
class F4FileHandler:
def __init__(self, filepath):
self.filepath = filepath
self.lines = []
def read_and_decode(self):
with open(self.filepath, 'r') as f:
self.lines = f.readlines()
print(f"Decoded properties for {self.filepath}:")
for idx, line in enumerate(self.lines):
padded = line.rstrip('\n').ljust(80)
col1 = padded[0]
is_comment = col1 in ('C', '*')
line_type = 'Comment' if is_comment else 'Statement'
label = 'N/A' if is_comment else padded[0:5].strip() or 'None'
continuation = padded[5] if padded[5] != ' ' else 'None'
statement = padded[6:72].strip()
identification = padded[72:80].strip() or 'None'
print(f"Line {idx + 1}:")
print(f" - Line Type: {line_type}")
print(f" - Label: {label}")
print(f" - Continuation Indicator: {continuation}")
print(f" - Statement Body: {statement}")
print(f" - Identification: {identification}")
print()
def write(self, output_path, properties_list):
"""
properties_list: list of dicts, each with keys: 'line_type', 'label', 'continuation', 'statement', 'identification'
"""
with open(output_path, 'w') as f:
for props in properties_list:
if props['line_type'] == 'Comment':
line = 'C' + ' ' * 4 + (props.get('continuation') or ' ') + props['statement'].ljust(66) + (props.get('identification') or '').rjust(8)
else:
label_str = (props.get('label') or '').rjust(5)
cont = props.get('continuation') or ' '
stmt = props['statement'].ljust(66)
id_str = (props.get('identification') or '').rjust(8)
line = label_str + cont + stmt + id_str
f.write(line[:80] + '\n')
print(f"Written to {output_path}")
# Example usage:
# handler = F4FileHandler('example.F4')
# handler.read_and_decode()
# properties = [{'line_type': 'Statement', 'label': '10', 'continuation': ' ', 'statement': 'PRINT *, "Hello"', 'identification': 'SEQ001'}]
# handler.write('output.F4', properties)
5. Java class for .F4 files
import java.io.*;
import java.util.ArrayList;
import java.util.List;
public class F4FileHandler {
private String filepath;
private List<String> lines = new ArrayList<>();
public F4FileHandler(String filepath) {
this.filepath = filepath;
}
public void readAndDecode() throws IOException {
try (BufferedReader reader = new BufferedReader(new FileReader(filepath))) {
String line;
while ((line = reader.readLine()) != null) {
lines.add(line);
}
}
System.out.println("Decoded properties for " + filepath + ":");
for (int idx = 0; idx < lines.size(); idx++) {
String padded = String.format("%-80s", lines.get(idx));
char col1 = padded.charAt(0);
boolean isComment = (col1 == 'C' || col1 == '*');
String lineType = isComment ? "Comment" : "Statement";
String label = isComment ? "N/A" : padded.substring(0, 5).trim().isEmpty() ? "None" : padded.substring(0, 5).trim();
String continuation = (padded.charAt(5) != ' ') ? String.valueOf(padded.charAt(5)) : "None";
String statement = padded.substring(6, 72).trim();
String identification = padded.substring(72, 80).trim().isEmpty() ? "None" : padded.substring(72, 80).trim();
System.out.println("Line " + (idx + 1) + ":");
System.out.println(" - Line Type: " + lineType);
System.out.println(" - Label: " + label);
System.out.println(" - Continuation Indicator: " + continuation);
System.out.println(" - Statement Body: " + statement);
System.out.println(" - Identification: " + identification);
System.out.println();
}
}
public void write(String outputPath, List<F4Property> propertiesList) throws IOException {
try (BufferedWriter writer = new BufferedWriter(new FileWriter(outputPath))) {
for (F4Property props : propertiesList) {
StringBuilder line = new StringBuilder();
if (props.lineType.equals("Comment")) {
line.append('C').append(" ").append(props.continuation != null ? props.continuation : " ")
.append(String.format("%-66s", props.statement))
.append(String.format("%8s", props.identification != null ? props.identification : ""));
} else {
line.append(String.format("%5s", props.label != null ? props.label : ""))
.append(props.continuation != null ? props.continuation : " ")
.append(String.format("%-66s", props.statement))
.append(String.format("%8s", props.identification != null ? props.identification : ""));
}
writer.write(line.substring(0, Math.min(80, line.length())) + "\n");
}
}
System.out.println("Written to " + outputPath);
}
public static class F4Property {
String lineType;
String label;
String continuation;
String statement;
String identification;
}
// Example usage:
// F4FileHandler handler = new F4FileHandler("example.F4");
// handler.readAndDecode();
// List<F4Property> props = new ArrayList<>();
// F4Property p = new F4Property();
// p.lineType = "Statement"; p.label = "10"; p.continuation = " "; p.statement = "PRINT *, \"Hello\""; p.identification = "SEQ001";
// props.add(p);
// handler.write("output.F4", props);
}
6. JavaScript class for .F4 files
Note: This is for Node.js, as browser JS can't directly open local files without user interaction (use the drag-and-drop from #3 for browser). It uses 'fs' module.
const fs = require('fs');
class F4FileHandler {
constructor(filepath) {
this.filepath = filepath;
this.lines = [];
}
readAndDecode() {
const content = fs.readFileSync(this.filepath, 'utf8');
this.lines = content.split(/\r?\n/);
console.log(`Decoded properties for ${this.filepath}:`);
this.lines.forEach((line, idx) => {
const padded = line.padEnd(80, ' ');
const col1 = padded[0];
const isComment = (col1 === 'C' || col1 === '*');
const lineType = isComment ? 'Comment' : 'Statement';
const label = isComment ? 'N/A' : padded.substring(0, 5).trim() || 'None';
const continuation = (padded[5] !== ' ') ? padded[5] : 'None';
const statement = padded.substring(6, 72).trim();
const identification = padded.substring(72, 80).trim() || 'None';
console.log(`Line ${idx + 1}:`);
console.log(` - Line Type: ${lineType}`);
console.log(` - Label: ${label}`);
console.log(` - Continuation Indicator: ${continuation}`);
console.log(` - Statement Body: ${statement}`);
console.log(` - Identification: ${identification}`);
console.log('');
});
}
write(outputPath, propertiesList) {
let content = '';
propertiesList.forEach(props => {
let line = '';
if (props.lineType === 'Comment') {
line = 'C' + ' '.repeat(4) + (props.continuation || ' ') + (props.statement || '').padEnd(66) + (props.identification || '').padStart(8);
} else {
line = (props.label || '').padStart(5) + (props.continuation || ' ') + (props.statement || '').padEnd(66) + (props.identification || '').padStart(8);
}
content += line.substring(0, 80) + '\n';
});
fs.writeFileSync(outputPath, content);
console.log(`Written to ${outputPath}`);
}
}
// Example usage:
// const handler = new F4FileHandler('example.F4');
// handler.readAndDecode();
// const properties = [{ lineType: 'Statement', label: '10', continuation: ' ', statement: 'PRINT *, "Hello"', identification: 'SEQ001' }];
// handler.write('output.F4', properties);
7. C class for .F4 files
Note: In C, we use structs instead of classes for simplicity, but here's a struct-based implementation with functions.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAX_LINES 1000
#define LINE_LEN 81 // 80 chars + null terminator
typedef struct {
char filepath[256];
char lines[MAX_LINES][LINE_LEN];
int line_count;
} F4FileHandler;
void init_f4_handler(F4FileHandler *handler, const char *filepath) {
strncpy(handler->filepath, filepath, 255);
handler->line_count = 0;
}
void read_and_decode(F4FileHandler *handler) {
FILE *fp = fopen(handler->filepath, "r");
if (!fp) {
perror("Error opening file");
return;
}
while (fgets(handler->lines[handler->line_count], LINE_LEN, fp) && handler->line_count < MAX_LINES) {
handler->line_count++;
}
fclose(fp);
printf("Decoded properties for %s:\n", handler->filepath);
for (int idx = 0; idx < handler->line_count; idx++) {
char padded[LINE_LEN];
strncpy(padded, handler->lines[idx], LINE_LEN - 1);
padded[LINE_LEN - 1] = '\0';
int len = strlen(padded);
memset(padded + len, ' ', LINE_LEN - 1 - len);
char col1 = padded[0];
int is_comment = (col1 == 'C' || col1 == '*');
const char *line_type = is_comment ? "Comment" : "Statement";
char label[6] = {0};
strncpy(label, padded, 5);
char *trim_label = strtok(label, " ");
const char *final_label = is_comment ? "N/A" : (trim_label ? trim_label : "None");
char continuation = padded[5];
const char *cont_str = (continuation != ' ') ? &continuation : "None"; // Single char, but as string
char statement[67] = {0};
strncpy(statement, padded + 6, 66);
char *trim_stmt = strtok(statement, "\0 "); // Trim trailing spaces
char id[9] = {0};
strncpy(id, padded + 72, 8);
char *trim_id = strtok(id, " ");
const char *final_id = trim_id ? trim_id : "None";
printf("Line %d:\n", idx + 1);
printf(" - Line Type: %s\n", line_type);
printf(" - Label: %s\n", final_label);
printf(" - Continuation Indicator: %s\n", cont_str); // Prints char or "None"
printf(" - Statement Body: %s\n", trim_stmt ? trim_stmt : "");
printf(" - Identification: %s\n", final_id);
printf("\n");
}
}
void write_f4(F4FileHandler *handler, const char *output_path, const char **properties_list, int prop_count) {
// properties_list is array of strings like "Statement|10| |PRINT *, \"Hello\"|SEQ001"
FILE *fp = fopen(output_path, "w");
if (!fp) {
perror("Error opening file");
return;
}
for (int i = 0; i < prop_count; i++) {
char line_type[10], label[6], continuation[2], statement[67], id[9];
sscanf(properties_list[i], "%[^|]|%[^|]|%[^|]|%[^|]|%s", line_type, label, continuation, statement, id);
char line[81];
if (strcmp(line_type, "Comment") == 0) {
snprintf(line, 81, "C %s%-66s%8s", continuation, statement, id);
} else {
snprintf(line, 81, "%5s%s%-66s%8s", label, continuation, statement, id);
}
fprintf(fp, "%s\n", line);
}
fclose(fp);
printf("Written to %s\n", output_path);
}
// Example usage:
// F4FileHandler handler;
// init_f4_handler(&handler, "example.F4");
// read_and_decode(&handler);
// const char *props[] = {"Statement|10| |PRINT *, \"Hello\"|SEQ001"};
// write_f4(&handler, "output.F4", props, 1);