IMPLEMENTATION MODULE Conversions;

PROCEDURE m2realstr(x : REAL; VAR s : ARRAY OF CHAR);
  EXTERNAL;

PROCEDURE m2strreal(VAR s : ARRAY OF CHAR; VAR ok : INTEGER) : REAL;
  EXTERNAL;

PROCEDURE IntToStr(n : INTEGER; VAR s : ARRAY OF CHAR);
  VAR v : INTEGER;
    i, k : CARDINAL;
    tmp : ARRAY [0 .. 31] OF CHAR;
BEGIN
  IF n = 0 THEN
    s[0] := "0"; s[1] := CHR(0)
  ELSE
    IF n < 0 THEN v := -n ELSE v := n END;
    i := 0;
    WHILE (v > 0) AND (i <= HIGH(tmp)) DO
      tmp[i] := CHR(ORD("0") + (v MOD 10));
      v := v DIV 10;
      INC(i)
    END;
    k := 0;
    IF n < 0 THEN s[k] := "-"; INC(k) END;
    WHILE (i > 0) AND (k <= HIGH(s)) DO
      DEC(i);
      s[k] := tmp[i]; INC(k)
    END;
    IF k <= HIGH(s) THEN s[k] := CHR(0) END
  END
END IntToStr;

PROCEDURE CardToStr(n : CARDINAL; VAR s : ARRAY OF CHAR);
  VAR v : CARDINAL;
    i, k : CARDINAL;
    tmp : ARRAY [0 .. 31] OF CHAR;
BEGIN
  IF n = 0 THEN
    s[0] := "0"; s[1] := CHR(0)
  ELSE
    v := n; i := 0;
    WHILE (v > 0) AND (i <= HIGH(tmp)) DO
      tmp[i] := CHR(ORD("0") + (v MOD 10));
      v := v DIV 10;
      INC(i)
    END;
    k := 0;
    WHILE (i > 0) AND (k <= HIGH(s)) DO
      DEC(i);
      s[k] := tmp[i]; INC(k)
    END;
    IF k <= HIGH(s) THEN s[k] := CHR(0) END
  END
END CardToStr;

PROCEDURE RealToStr(x : REAL; VAR s : ARRAY OF CHAR);
BEGIN
  m2realstr(x, s)
END RealToStr;

PROCEDURE StrToInt(s : ARRAY OF CHAR; VAR n : INTEGER) : BOOLEAN;
  VAR i : CARDINAL;
    neg, seen : BOOLEAN;
    v : INTEGER;
BEGIN
  n := 0; i := 0; neg := FALSE; seen := FALSE; v := 0;
  IF (i > HIGH(s)) OR (s[i] = CHR(0)) THEN RETURN FALSE END;
  IF s[i] = "-" THEN neg := TRUE; INC(i)
  ELSIF s[i] = "+" THEN INC(i)
  END;
  WHILE (i <= HIGH(s)) AND (s[i] >= "0") AND (s[i] <= "9") DO
    v := v * 10 + (ORD(s[i]) - ORD("0"));
    seen := TRUE;
    INC(i)
  END;
  IF NOT seen THEN RETURN FALSE END;
  IF (i <= HIGH(s)) AND (s[i] # CHR(0)) THEN RETURN FALSE END;
  IF neg THEN n := -v ELSE n := v END;
  RETURN TRUE
END StrToInt;

PROCEDURE StrToCard(s : ARRAY OF CHAR; VAR n : CARDINAL) : BOOLEAN;
  VAR i : CARDINAL;
    seen : BOOLEAN;
    v : CARDINAL;
BEGIN
  n := 0; i := 0; seen := FALSE; v := 0;
  WHILE (i <= HIGH(s)) AND (s[i] >= "0") AND (s[i] <= "9") DO
    v := v * 10 + (ORD(s[i]) - ORD("0"));
    seen := TRUE;
    INC(i)
  END;
  IF NOT seen THEN RETURN FALSE END;
  IF (i <= HIGH(s)) AND (s[i] # CHR(0)) THEN RETURN FALSE END;
  n := v;
  RETURN TRUE
END StrToCard;

PROCEDURE StrToReal(VAR s : ARRAY OF CHAR; VAR x : REAL) : BOOLEAN;
  VAR ok : INTEGER;
BEGIN
  x := m2strreal(s, ok);
  RETURN ok # 0
END StrToReal;

END Conversions.