diff --git a/lex.c b/lex.c
index fd724c3..fabe3d9 100644
--- a/lex.c
+++ b/lex.c
@@ -1,17 +1,23 @@
+#include <ctype.h>
+
 #include "picoc.h"
 
+
+#define isCidstart(c) (isalpha(c) || (c)=='_')
+
 #define LEXINC Lexer->Pos++
 #define NEXTIS(c,x,y) { if (NextChar == (c)) { LEXINC; return (x); } else return (y); }
 #define NEXTIS3(c,x,d,y,z) { if (NextChar == (c)) { LEXINC; return (x); } else NEXTIS(d,y,z) }
 #define NEXTIS4(c,x,d,y,e,z,a) { if (NextChar == (c)) { LEXINC; return (x); } else NEXTIS3(d,y,e,z,a) }
 
+
 struct ReservedWord
 {
     const char *Word;
     enum LexToken Token;
 };
 
-static char *ReservedWords[] =
+static struct ReservedWord ReservedWords[] =
 {
     { "char", TokenCharType },
     { "do", TokenDo },
@@ -23,11 +29,12 @@ static char *ReservedWords[] =
     { "void", TokenVoidType }
 };
 
-void LexInit(struct LexState *Lexer, const Str *Source, int Line)
+void LexInit(struct LexState *Lexer, const Str *Source, const Str *FileName, int Line)
 {
     Lexer->Pos = Source->Str;
     Lexer->End = Source->Str + Source->Len;
     Lexer->Line = Line;
+    Lexer->FileName = FileName;
 }
 
 
@@ -37,8 +44,8 @@ enum LexToken LexCheckReservedWord(const Str *Word)
     
     for (Count = 0; Count < sizeof(ReservedWords) / sizeof(struct ReservedWord); Count++)
     {
-        if (StrEqualC(Word, ReservedWord[Count].Word))
-            return ReservedWord[Count].Token;
+        if (StrEqualC(Word, ReservedWords[Count].Word))
+            return ReservedWords[Count].Token;
     }
     
     return TokenNone;
@@ -47,13 +54,29 @@ enum LexToken LexCheckReservedWord(const Str *Word)
 
 enum LexToken LexGetNumber(struct LexState *Lexer)
 {
-    XXX
+    // XXX
+    return TokenIntegerConstant;
 }
 
 
 enum LexToken LexGetWord(struct LexState *Lexer)
 {
-    XXX
+    // XXX
+    return TokenIdentifier;
+}
+
+
+enum LexToken LexGetStringConstant(struct LexState *Lexer)
+{
+    // XXX
+    return TokenStringConstant;
+}
+
+
+enum LexToken LexGetCharacterConstant(struct LexState *Lexer)
+{
+    // XXX
+    return TokenCharacterConstant;
 }
 
 
@@ -83,14 +106,14 @@ enum LexToken LexGetToken(struct LexState *Lexer)
         case '\'': return LexGetCharacterConstant(Lexer);
         case '(': return TokenOpenBracket;
         case ')': return TokenCloseBracket;
-        case '=': NEXTIS('=', TokenEquality, TokenAssignment);
+        case '=': NEXTIS('=', TokenEquality, TokenAssign);
         case '+': NEXTIS3('=', TokenAddAssign, '+', TokenIncrement, TokenPlus);
         case '-': NEXTIS4('=', TokenSubtractAssign, '>', TokenArrow, '-', TokenDecrement, TokenMinus);
         case '*': return TokenAsterisk;
         case '/': return TokenSlash;
-        case '<': NEXTIS('=', TokenLessEqual, TokenLess);
-        case '>': NEXTIS('=', TokenGreaterEqual, TokenGreater);
-        case ';': return TokenSemiColon;
+        case '<': NEXTIS('=', TokenLessEqual, TokenLessThan);
+        case '>': NEXTIS('=', TokenGreaterEqual, TokenGreaterThan);
+        case ';': return TokenSemicolon;
         case '&': NEXTIS('&', TokenLogicalAnd, TokenAmpersand);
         case '|': NEXTIS('|', TokenLogicalOr, TokenArithmeticOr);
         case '{': return TokenLeftBrace;
diff --git a/picoc.c b/picoc.c
index 61eedde..69ffbaa 100644
--- a/picoc.c
+++ b/picoc.c
@@ -22,7 +22,7 @@ void ProgramError(const Str *FileName, int Line, const char *Message, ...)
 {
     va_list Args;
 
-    StrPrintf("%S:%d: ", FileName, Line)    
+    StrPrintf("%S:%d: ", FileName, Line);   
     va_start(Args, Message);
     vprintf(Message, Args);
     printf("\n");
diff --git a/picoc.h b/picoc.h
index a2c6011..8b91ae3 100644
--- a/picoc.h
+++ b/picoc.h
@@ -111,6 +111,7 @@ struct LexState
     int Line;
     const char *Pos;
     const char *End;
+    const Str *FileName;
 };
 
 
@@ -119,7 +120,7 @@ void StrToC(char *Dest, int DestSize, const Str *Source);
 void StrFromC(Str *Dest, const char *Source);
 int StrEqual(const Str *Str1, const Str *Str2);
 int StrEqualC(const Str *Str1, const char *Str2);
-void StrPrintf(const str *Format, ...);
+void StrPrintf(const char *Format, ...);
 
 /* picoc.c */
 void Fail(const char *Message, ...);
@@ -132,8 +133,8 @@ void TableSet(struct Table *Tbl, const Str *Key, void *Value);
 void *TableLookup(struct Table *Tbl, const Str *Key);
 
 /* lex.c */
-void LexInit(const Str *Source);
-enum LexToken LexGetToken(void);
+void LexInit(struct LexState *Lexer, const Str *Source, const Str *FileName, int Line);
+enum LexToken LexGetToken(struct LexState *Lexer);
 
 /* parse.c */
 void ParseInit(void);
diff --git a/str.c b/str.c
index e108fd2..c8b8bcb 100644
--- a/str.c
+++ b/str.c
@@ -1,3 +1,4 @@
+#include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <stdarg.h>
@@ -35,21 +36,35 @@ int StrEqualC(const Str *Str1, const char *Str2)
 }
 
 
-void StrPrintf(const str *Format, ...)
+void StrPrintf(const char *Format, ...)
 {
-    char FormatBuf[MAX_FORMAT];
     const char *FPos;
-    char *BPos;
     va_list Args;
+    Str *str;
     
     va_start(Args, Format);
-    for (FPos = Format, BPos = &FormatBuf[0]; *FPos != '\0'; FPos++, BPos++)
+    for (FPos = Format; *FPos != '\0'; FPos++)
     {
         if (*FPos == '%')
         {
-            XXX
+            FPos++;
+            switch (*FPos)
+            {
+            case 'S':
+                str = va_arg(Args, Str *);
+                fwrite(str->Str, 1, str->Len, stdout);
+                break;
+                
+            case 's': fputs(va_arg(Args, char *), stdout); break;
+            case 'd': printf("%d", va_arg(Args, int)); break;
+            case 'c': fputc(va_arg(Args, int), stdout); break;
+            case '%': fputc('%', stdout); break;
+            case '\0': FPos--; break;
+            }
         }
-        *BPos = *FPos;
+        else
+            putchar(*FPos);
     }
+    va_end(Args);
 }