hoc 2.3 KB

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  1. .TH HOC 1
  2. .SH NAME
  3. hoc \- interactive floating point language
  4. .SH SYNOPSIS
  5. .B hoc
  6. [
  7. .B -e
  8. .I expression
  9. ]
  10. [
  11. .I file ...
  12. ]
  13. .SH DESCRIPTION
  14. .I Hoc
  15. interprets a simple language for floating point arithmetic,
  16. at about the level of BASIC, with C-like syntax and
  17. functions.
  18. .PP
  19. The named
  20. .I files
  21. are read and interpreted in order.
  22. If no
  23. .I file
  24. is given or if
  25. .I file
  26. is
  27. .L -
  28. .I hoc
  29. interprets the standard input.
  30. The
  31. .B -e
  32. option allows input to
  33. .I hoc
  34. to be specified on the command line, to be treated as if it appeared in a file.
  35. .PP
  36. .I Hoc
  37. input consists of
  38. .I expressions
  39. and
  40. .IR statements .
  41. Expressions are evaluated and their results printed.
  42. Statements, typically assignments and function or procedure
  43. definitions, produce no output unless they explicitly call
  44. .IR print .
  45. .PP
  46. Variable names have the usual syntax, including
  47. .LR _ ;
  48. the name
  49. .L _
  50. by itself contains the value of the last expression evaluated.
  51. The variables
  52. .BR E ,
  53. .BR PI ,
  54. .BR PHI ,
  55. .BR GAMMA
  56. and
  57. .B DEG
  58. are predefined; the last is 59.25..., degrees per radian.
  59. .PP
  60. Expressions are formed with these C-like operators, listed by
  61. decreasing precedence.
  62. .TP
  63. .B ^
  64. exponentiation
  65. .TP
  66. .B ! - ++ --
  67. .TP
  68. .B * / %
  69. .TP
  70. .B + -
  71. .TP
  72. .B > >= < <= == !=
  73. .TP
  74. .B &&
  75. .TP
  76. .B ||
  77. .TP
  78. .B = += -= *= /= %=
  79. .PP
  80. Built in functions are
  81. .BR abs ,
  82. .BR acos ,
  83. .BR asin ,
  84. .B atan
  85. (one argument),
  86. .BR cos ,
  87. .BR cosh ,
  88. .BR exp ,
  89. .BR int ,
  90. .BR log ,
  91. .BR log10 ,
  92. .BR sin ,
  93. .BR sinh ,
  94. .BR sqrt ,
  95. .BR tan ,
  96. and
  97. .BR tanh .
  98. The function
  99. .B read(x)
  100. reads a value into the variable
  101. .B x
  102. and returns 0 at EOF;
  103. the statement
  104. .B print
  105. prints a list of expressions that may include
  106. string constants such as
  107. \fL"hello\en"\f1.\fP
  108. .PP
  109. Control flow statements are
  110. .BR if - else ,
  111. .BR while ,
  112. and
  113. .BR for ,
  114. with braces for grouping.
  115. Newline ends a statement.
  116. Backslash-newline is equivalent to a space.
  117. .PP
  118. Functions and procedures are introduced by the words
  119. .B func
  120. and
  121. .BR proc ;
  122. .B return
  123. is used to return with a value from a function.
  124. .SH EXAMPLES
  125. .EX
  126. func gcd(a, b) {
  127. temp = abs(a) % abs(b)
  128. if(temp == 0) return abs(b)
  129. return gcd(b, temp)
  130. }
  131. for(i=1; i<12; i++) print gcd(i,12)
  132. .EE
  133. .SH SOURCE
  134. .B /sys/src/cmd/hoc
  135. .SH "SEE ALSO"
  136. .IR bc (1),
  137. .IR dc (1)
  138. .br
  139. B. W. Kernighan and R. Pike,
  140. .I
  141. The Unix Programming Environment,
  142. Prentice-Hall, 1984
  143. .SH BUGS
  144. Error recovery is imperfect within function and procedure definitions.