package com.horstmann; import java.io.*; /** A class for formatting numbers that follows printf conventions. Also implements C-like atoi and atof functions @version 1.21 2000-06-09 @author Cay Horstmann 1998-09-14: Fixed a number of bugs. 1.Formatting the most extreme negative number (-9223372036854775808L) printed with 2 leading minus signs. 2.Printing 0 with a %e or %g format did not work. 3.Printing numbers that were closer to 1 than the number of requested decimal places rounded down rather than up, e.g. formatting 1.999 with %.2f printed 1.00. (This one is pretty serious, of course.) 4.Printing with precision 0 (e.g %10.0f) didn't work. 5.Printing a string with a precision that exceeded the string length (e.g. print "Hello" with %20.10s) caused a StringIndexOutOfBounds error. 1998-10-21: Changed method names from print to printf 2000-06-09: Moved to package com.horstmann; no longer part of Core Java 2000-06-09: Fixed a number of bugs. 1.Printing 100.0 with %e printed 10.0e1, not 1.0e2 2.Printing Inf and NaN didn't work. 2000-06-09: Coding guideline cleanup */ public class Format { /** Formats the number following printf conventions. Main limitation: Can only handle one format parameter at a time Use multiple Format objects to format more than one number @param s the format string following printf conventions The string has a prefix, a format code and a suffix. The prefix and suffix become part of the formatted output. The format code directs the formatting of the (single) parameter to be formatted. The code has the following structure @exception IllegalArgumentException if bad format */ public Format(String s) { width = 0; precision = -1; pre = ""; post = ""; leadingZeroes = false; showPlus = false; alternate = false; showSpace = false; leftAlign = false; fmt = ' '; int state = 0; int length = s.length(); int parseState = 0; // 0 = prefix, 1 = flags, 2 = width, 3 = precision, // 4 = format, 5 = end int i = 0; while (parseState == 0) { if (i >= length) parseState = 5; else if (s.charAt(i) == '%') { if (i < length - 1) { if (s.charAt(i + 1) == '%') { pre = pre + '%'; i++; } else parseState = 1; } else throw new java.lang.IllegalArgumentException(); } else pre = pre + s.charAt(i); i++; } while (parseState == 1) { if (i >= length) parseState = 5; else if (s.charAt(i) == ' ') showSpace = true; else if (s.charAt(i) == '-') leftAlign = true; else if (s.charAt(i) == '+') showPlus = true; else if (s.charAt(i) == '0') leadingZeroes = true; else if (s.charAt(i) == '#') alternate = true; else { parseState = 2; i--; } i++; } while (parseState == 2) { if (i >= length) parseState = 5; else if ('0' <= s.charAt(i) && s.charAt(i) <= '9') { width = width * 10 + s.charAt(i) - '0'; i++; } else if (s.charAt(i) == '.') { parseState = 3; precision = 0; i++; } else parseState = 4; } while (parseState == 3) { if (i >= length) parseState = 5; else if ('0' <= s.charAt(i) && s.charAt(i) <= '9') { precision = precision * 10 + s.charAt(i) - '0'; i++; } else parseState = 4; } if (parseState == 4) { if (i >= length) parseState = 5; else fmt = s.charAt(i); i++; } if (i < length) post = s.substring(i, length); } /** prints a formatted number following printf conventions @param fmt the format string @param x the double to print */ public static void printf(String fmt, double x) { System.out.print(new Format(fmt).format(x)); } /** prints a formatted number following printf conventions @param fmt the format string @param x the int to print */ public static void printf(String fmt, int x) { System.out.print(new Format(fmt).format(x)); } /** prints a formatted number following printf conventions @param fmt the format string @param x the long to print */ public static void printf(String fmt, long x) { System.out.print(new Format(fmt).format(x)); } /** prints a formatted number following printf conventions @param fmt the format string @param x the character to print */ public static void printf(String fmt, char x) { System.out.print(new Format(fmt).format(x)); } /** prints a formatted number following printf conventions @param fmt the format string @param x a string to print */ public static void printf(String fmt, String x) { System.out.print(new Format(fmt).format(x)); } /** Converts a string of digits (decimal, octal or hex) to an integer @param s a string @return the numeric value of the prefix of s representing a base 10 integer */ public static int atoi(String s) { return (int)atol(s); } /** Converts a string of digits (decimal, octal or hex) to a long integer @param s a string @return the numeric value of the prefix of s representing a base 10 integer */ public static long atol(String s) { int i = 0; while (i < s.length() && Character.isWhitespace(s.charAt(i))) i++; if (i < s.length() && s.charAt(i) == '0') { if (i + 1 < s.length() && (s.charAt(i + 1) == 'x' || s.charAt(i + 1) == 'X')) return parseLong(s.substring(i + 2), 16); else return parseLong(s, 8); } else return parseLong(s, 10); } private static long parseLong(String s, int base) { int i = 0; int sign = 1; long r = 0; while (i < s.length() && Character.isWhitespace(s.charAt(i))) i++; if (i < s.length() && s.charAt(i) == '-') { sign = -1; i++; } else if (i < s.length() && s.charAt(i) == '+') { i++; } while (i < s.length()) { char ch = s.charAt(i); if ('0' <= ch && ch < '0' + base) r = r * base + ch - '0'; else if ('A' <= ch && ch < 'A' + base - 10) r = r * base + ch - 'A' + 10 ; else if ('a' <= ch && ch < 'a' + base - 10) r = r * base + ch - 'a' + 10 ; else return r * sign; i++; } return r * sign; } /** Converts a string of digits to a double @param s a string */ public static double atof(String s) { int i = 0; int sign = 1; double r = 0; // integer part double f = 0; // fractional part double p = 1; // exponent of fractional part int state = 0; // 0 = int part, 1 = frac part while (i < s.length() && Character.isWhitespace(s.charAt(i))) i++; if (i < s.length() && s.charAt(i) == '-') { sign = -1; i++; } else if (i < s.length() && s.charAt(i) == '+') { i++; } while (i < s.length()) { char ch = s.charAt(i); if ('0' <= ch && ch <= '9') { if (state == 0) r = r * 10 + ch - '0'; else if (state == 1) { p = p / 10; r = r + p * (ch - '0'); } } else if (ch == '.') { if (state == 0) state = 1; else return sign * r; } else if (ch == 'e' || ch == 'E') { long e = (int)parseLong(s.substring(i + 1), 10); return sign * r * Math.pow(10, e); } else return sign * r; i++; } return sign * r; } /** Formats a double into a string (like sprintf in C) @param x the number to format @return the formatted string @exception IllegalArgumentException if bad argument */ public String format(double x) { String r; if (precision < 0) precision = 6; int s = 1; if (x < 0) { x = -x; s = -1; } if (Double.isNaN(x)) r = "NaN"; else if (x == Double.POSITIVE_INFINITY) r = "Inf"; else if (fmt == 'f') r = fixedFormat(x); else if (fmt == 'e' || fmt == 'E' || fmt == 'g' || fmt == 'G') r = expFormat(x); else throw new java.lang.IllegalArgumentException(); return pad(sign(s, r)); } /** Formats an integer into a string (like sprintf in C) @param x the number to format @return the formatted string */ public String format(int x) { long lx = x; if (fmt == 'o' || fmt == 'x' || fmt == 'X') lx &= 0xFFFFFFFFL; return format(lx); } /** Formats a long integer into a string (like sprintf in C) @param x the number to format @return the formatted string */ public String format(long x) { String r; int s = 0; if (fmt == 'd' || fmt == 'i') { if (x < 0) { r = ("" + x).substring(1); s = -1; } else { r = "" + x; s = 1; } } else if (fmt == 'o') r = convert(x, 3, 7, "01234567"); else if (fmt == 'x') r = convert(x, 4, 15, "0123456789abcdef"); else if (fmt == 'X') r = convert(x, 4, 15, "0123456789ABCDEF"); else throw new java.lang.IllegalArgumentException(); return pad(sign(s, r)); } /** Formats a character into a string (like sprintf in C) @param x the value to format @return the formatted string */ public String format(char c) { if (fmt != 'c') throw new java.lang.IllegalArgumentException(); String r = "" + c; return pad(r); } /** Formats a string into a larger string (like sprintf in C) @param x the value to format @return the formatted string */ public String format(String s) { if (fmt != 's') throw new java.lang.IllegalArgumentException(); if (precision >= 0 && precision < s.length()) s = s.substring(0, precision); return pad(s); } /** a test stub for the format class */ public static void main(String[] a) { double x = 1.23456789012; double y = 123; double z = 1.2345e30; double w = 1.02; double u = 1.234e-5; int d = 0xCAFE; Format.printf("x = |%f|\n", x); Format.printf("u = |%20f|\n", u); Format.printf("x = |% .5f|\n", x); Format.printf("w = |%20.5f|\n", w); Format.printf("x = |%020.5f|\n", x); Format.printf("x = |%+20.5f|\n", x); Format.printf("x = |%+020.5f|\n", x); Format.printf("x = |% 020.5f|\n", x); Format.printf("y = |%#+20.5f|\n", y); Format.printf("y = |%-+20.5f|\n", y); Format.printf("z = |%20.5f|\n", z); Format.printf("x = |%e|\n", x); Format.printf("u = |%20e|\n", u); Format.printf("x = |% .5e|\n", x); Format.printf("w = |%20.5e|\n", w); Format.printf("x = |%020.5e|\n", x); Format.printf("x = |%+20.5e|\n", x); Format.printf("x = |%+020.5e|\n", x); Format.printf("x = |% 020.5e|\n", x); Format.printf("y = |%#+20.5e|\n", y); Format.printf("y = |%-+20.5e|\n", y); Format.printf("x = |%g|\n", x); Format.printf("z = |%g|\n", z); Format.printf("w = |%g|\n", w); Format.printf("u = |%g|\n", u); Format.printf("y = |%.2g|\n", y); Format.printf("y = |%#.2g|\n", y); Format.printf("d = |%d|\n", d); Format.printf("d = |%20d|\n", d); Format.printf("d = |%020d|\n", d); Format.printf("d = |%+20d|\n", d); Format.printf("d = |% 020d|\n", d); Format.printf("d = |%-20d|\n", d); Format.printf("d = |%20.8d|\n", d); Format.printf("d = |%x|\n", d); Format.printf("d = |%20X|\n", d); Format.printf("d = |%#20x|\n", d); Format.printf("d = |%020X|\n", d); Format.printf("d = |%20.8x|\n", d); Format.printf("d = |%o|\n", d); Format.printf("d = |%020o|\n", d); Format.printf("d = |%#20o|\n", d); Format.printf("d = |%#020o|\n", d); Format.printf("d = |%20.12o|\n", d); Format.printf("s = |%-20s|\n", "Hello"); Format.printf("s = |%-20c|\n", '!'); // regression test to confirm fix of reported bugs Format.printf("|%i|\n", Long.MIN_VALUE); Format.printf("|%6.2e|\n", 0.0); Format.printf("|%6.2g|\n", 0.0); Format.printf("|%6.2f|\n", 9.99); Format.printf("|%6.2f|\n", 9.999); Format.printf("|%.2f|\n", 1.999); Format.printf("|%6.0f|\n", 9.999); Format.printf("|%20.10s|\n", "Hello"); d = -1; Format.printf("-1 = |%X|\n", d); Format.printf("100 = |%e|\n", 100.0); // 2000-06-09 Format.printf("1/0 = |%f|\n", 1.0 / 0.0); Format.printf("-1/0 = |%e|\n", -1.0 / 0.0); Format.printf("0/0 = |%g|\n", 0.0 / 0.0); } private static String repeat(char c, int n) { if (n <= 0) return ""; StringBuffer s = new StringBuffer(n); for (int i = 0; i < n; i++) s.append(c); return s.toString(); } private static String convert(long x, int n, int m, String d) { if (x == 0) return "0"; String r = ""; while (x != 0) { r = d.charAt((int)(x & m)) + r; x = x >>> n; } return r; } private String pad(String r) { String p = repeat(' ', width - r.length()); if (leftAlign) return pre + r + p + post; else return pre + p + r + post; } private String sign(int s, String r) { String p = ""; if (s < 0) p = "-"; else if (s > 0) { if (showPlus) p = "+"; else if (showSpace) p = " "; } else { if (fmt == 'o' && alternate && r.length() > 0 && r.charAt(0) != '0') p = "0"; else if (fmt == 'x' && alternate) p = "0x"; else if (fmt == 'X' && alternate) p = "0X"; } int w = 0; if (leadingZeroes) w = width; else if ((fmt == 'd' || fmt == 'i' || fmt == 'x' || fmt == 'X' || fmt == 'o') && precision > 0) w = precision; return p + repeat('0', w - p.length() - r.length()) + r; } private String fixedFormat(double d) { boolean removeTrailing = (fmt == 'G' || fmt == 'g') && !alternate; // remove trailing zeroes and decimal point if (d > 0x7FFFFFFFFFFFFFFFL) return expFormat(d); if (precision == 0) return (long)(d + 0.5) + (removeTrailing ? "" : "."); long whole = (long)d; double fr = d - whole; // fractional part if (fr >= 1 || fr < 0) return expFormat(d); double factor = 1; String leadingZeroes = ""; for (int i = 1; i <= precision && factor <= 0x7FFFFFFFFFFFFFFFL; i++) { factor *= 10; leadingZeroes = leadingZeroes + "0"; } long l = (long) (factor * fr + 0.5); if (l >= factor) { l = 0; whole++; } // CSH 10-25-97 String z = leadingZeroes + l; z = "." + z.substring(z.length() - precision, z.length()); if (removeTrailing) { int t = z.length() - 1; while (t >= 0 && z.charAt(t) == '0') t--; if (t >= 0 && z.charAt(t) == '.') t--; z = z.substring(0, t + 1); } return whole + z; } private String expFormat(double d) { String f = ""; int e = 0; double dd = d; double factor = 1; if (d != 0) { while (dd >= 10) { e++; factor /= 10; dd = dd / 10; } // 2000-06-09 while (dd < 1) { e--; factor *= 10; dd = dd * 10; } } if ((fmt == 'g' || fmt == 'G') && e >= -4 && e < precision) return fixedFormat(d); d = d * factor; f = f + fixedFormat(d); if (fmt == 'e' || fmt == 'g') f = f + "e"; else f = f + "E"; String p = "000"; if (e >= 0) { f = f + "+"; p = p + e; } else { f = f + "-"; p = p + (-e); } return f + p.substring(p.length() - 3, p.length()); } private int width; private int precision; private String pre; private String post; private boolean leadingZeroes; private boolean showPlus; private boolean alternate; private boolean showSpace; private boolean leftAlign; private char fmt; // one of cdeEfgGiosxXos }