A very basic printf procedure

[Arnold]

Hi Charles,

I used \examples\DataProcessing\Format1.o2bas to create a printf procedure for some (very) basic C-like formatted output. The code so far is:

Code: OxygenBasic

1. include "$/inc/console.inc"
2.  
3.  
4.   sub printf(string sf,...)
5.   '========================
6.  sys p=@sf+sizeof sys
7.  
8.   sys     iv at p 'integers  
9.  bstring sv at p 'string
10.  double  dv at p 'double
11.  float   fv at p 'float
12.  
13.   sys i
14.   string outp=sf
15.  
16.   do
17.     i++ : if i>len(outp) then exit do
18.    
19.     select asc outp,i
20.     case "%"
21.       if mid(outp,i+1,1) = "s" then  outp=left(outp,i-1) & sv & mid(outp,i+2): p+=sizeof sys
22.       if mid(outp,i+1,1) = "d" or mid(outp,i+1,1) = "i" then  
23.          outp=left(outp,i-1) & str(iv) & mid(outp,i+2): p+=sizeof sys
24.       end if              
25.       if mid(outp,i+1,1) = "f" then outp=left(outp,i-1) + str(fv) + mid(outp,i+2): p+=sizeof float
26.       if mid(outp,i+1,1) = "g" then outp=left(outp,i-1) + str(dv) + mid(outp,i+2): p+=sizeof double
27.          
28.     end select
29.   end do
30.  
31.   'replace \n
32.  do
33.     i=instr(outp,"\n")
34.     if i then
35.       outp=left(outp,i-1)+chr(10)+mid(outp,i+2)
36.     else
37.       exit do
38.     end if
39.   end do
40.    
41.   print outp
42.   end sub
43.  
44.  
45.   'TEST
46.  '====
47. printf("A very basic printf procedure\n", "and therefore not foolproof")
48. printf("not %d% safe\n", 100)
49. printf(42)
50. printf("\n%d\n",1+3)
51. printf "The Eiffel Tower is located in %s\nand it's height is %d ft.\n", "Paris", 986
52. printf("Pi = %s\n", str(pi,3))
53.  
54. float x=1.5f
55. double x1= x
56. printf ("x = %f\n", x)
57. printf ("x = %g", x)    'false
58. printf ("\nx1 = %g\n", x1)
59. printf ("100 = hex %s\n", hex(100) )
60.  
61. print "Enter ...": waitkey()
62.  
63.  

Can this code be optimized in some way? I would only need some basic modifiers, but I am not sure when using e.g. "%f" if it is possible to recognize some different types like float, single, double, quad and treat them differently? In the simplest case I will use "%s" in combination with str(value).


Roland

[Charles Pegge]

Hi Roland,

You can access the real thing:

sprintf_s

Code: OxygenBasic

1. extern lib "MSVCRT.dll" cdecl
2. sys  sprintf_s(char *buf, sys size, char *format, ...)
3. end extern
4.  

Mike and I had console redirection trouble using printf directly, but you can feed the buffer output of sprintf, wherever it is required.

[JRS]

O2C 

[Charles Pegge]

A customised interpretation of sprinf, using byte-wise parsing and a fixed string buffer. Minimises use of temp strings:

Code: OxygenBasic

1. function sprintf(char* fmt,...) as string
2. =========================================
3. indexbase 0
4. sys    p=@param[1]      'current param pointer
5. string s=nuls 300       'output buffer
6. string v                'value string
7. byte   bs at strptr fmt 'bytes source
8. byte   bd at strptr s   'bytes dest
9. sys    id=1             'output buffer index
10. sys    sy=sizeof sys    'stack width = 4bytes/8bytes
11. sys lv                  'length of value string
12. do
13.   lv=1 'default
14.  select bs
15.   case 0
16.     bd=0
17.     exit do
18.   case "%"
19.     @bs++
20.     select bs
21.     case "i"  : int u at p    : v=str(round(u)) : p+=sy : mid(s,id)=v : lv=len v
22.     case "g"  : float u at p  : v=str(u) : p+=sy : mid(s,id)=v : lv=len v
23.     case "f"  : double u at p : v=str(u) : p+=sizeof u : mid(s,id)=v : lv=len v
24.     case "s"  : char u at *p  : p+=sy : mid(s,id)=u : lv=len u
25.     case else : bd=bs
26.     end select
27.   case "\"
28.     @bs++
29.     select bs
30.     case "t"  : bd=9
31.     case "n"  : bd=10
32.     case else : bd=bs
33.     end select
34.   case else : bd=bs
35.   end select
36.   @bs++ : @bd+=lv : id+=lv 'NEXT POSITIONS
37. end do
38. return left s,id-1
39. end function
40.  
41. print sprintf "string=%s\ndouble=%f\n","abcdef",-123.45E1
42.  

[JRS]

Code: Script BASIC

1. print format("string=%s\ndouble=%f\n","abcdef",-123.45E1)
2.  

jrs@laptop:~/sb/sb22/test$ scriba printf.sb
string=abcdef
double=-1234.500000
jrs@laptop:~/sb/sb22/test$


A different approach.

Code: Script BASIC

1. print "string=abcdef\ndouble=",format("%~-###0.0000\n~",-123.45E1)
2.  

jrs@laptop:~/sb/sb22/test$ scriba fmt2.sb
string=abcdef
double=-1234.5000
jrs@laptop:~/sb/sb22/test$

[Arnold]

Hi Charles,

thank you for this piece of code. It is very instructive and it is totally sufficient for my intended use. (using sprintf_s is not essential necessary). I modified the code a little bit to use it as sprintf function and printf procedure:

Code: OxygenBasic

1. include "$/inc/console.inc"
2.  
3. macro do_sprintf(format, ...)
4. indexbase 0
5. sys    p=@param[1]      'current param pointer
6. string s=nuls 300       'output buffer
7. string v                'value string
8. byte   bs at strptr fmt 'bytes source
9. byte   bd at strptr s   'bytes dest
10. sys    id=1             'output buffer index
11. sys    sy=sizeof sys    'stack width = 4bytes/8bytes
12. sys lv                  'length of value string
13. do
14.   lv=1 'default
15.  select bs
16.   case 0
17.     bd=0
18.     exit do
19.   case "%"
20.     @bs++
21.     select bs
22.     case "i","d" : int u at p : v=str(round(u)) : p+=sy : mid(s,id)=v : lv=len v
23.     case "g"  : float u at p  : v=str(u) : p+=sy : mid(s,id)=v : lv=len v
24.     case "f"  : double u at p : v=str(u) : p+=sizeof u : mid(s,id)=v : lv=len v
25.     case "s"  : char u at *p  : p+=sy : mid(s,id)=u : lv=len u
26.     case "x"  : char u at *p  : p+=sy : mid(s,id)="0x" & u : lv=len(u)+2  
27.     case else : bd=bs
28.     end select
29.   case "\"
30.     @bs++
31.     select bs
32.     case "t"  : bd=9
33.     case "n"  : bd=10
34.     case else : bd=bs
35.     end select
36.   case else : bd=bs
37.   end select
38.   @bs++ : @bd+=lv : id+=lv 'NEXT POSITIONS
39. end do
40. id-=1
41.  
42. end macro
43.  
44. function sprintf(char* fmt,...) as string
45. =========================================
46.    do_sprintf(fmt, ...)
47.    return left s,id
48. end function
49.  
50.  
51. sub printf(char* fmt,...)
52. =========================
53.    do_sprintf(fmt,...)
54.    print left s,id
55. end sub
56.  
57. print sprintf "string=%s\ndouble=%f\n","abcdef",-123.45E1
58. printf "string=%s\ndouble=%f\n","abcdef",-123.45E1
59.  
60.   'TEST                    
61.  '====
62.  
63. printf("\nA very basic printf procedure", "and therefore not foolproof")  ' mini joke
64. printf(`\nnot %d%% "safe"\n`, 100)
65. printf(42)
66. printf("\n%d\n",1+3)
67. printf "The Eiffel Tower is located in %s\nand it's height is %d ft.\n", "Paris", 986
68. printf "To Pi = %s or not to Pi = %s\n", str(pi,3), str(-pi,4)
69.  
70. float x=1.5f
71. double x1= x
72. printf ("x = %g\n", x)
73. printf ("false x = %f", x) ' false
74. printf ("\ncorrect x1 = %f\n", x1)
75. printf ("10011 = hex %x\n", hex 10011 )
76. printf ("The End\n")
77.  
78. print "Enter ...": waitkey()
79.  

this works quite nice and I will use printf in the remaining test cases of Iup 3.14.

Roland

.

[JRS]

Nice job Roland & Charles!

That is going to make IUP in O2 much easier to use.