Equation or not?

[Han]

This program returns the index (in L0) of the formula having only = as the "comparison" operator. You can easily change it to p(0):=L0(j); rather than p(0):=j; Note that we are assuming the strings are validly formed inequalities/equalities.

PHP Code:

export findeq()
begin

local j,k,n,m,p;

L0:={"x+y=1","2x+2y<2","3x+3y<=3","4x+4y≤4","5x+5y>5","6x+6y>=6","7x+7y≥7","8x+8y<>8","9x+9y≠9"};
L1:={"<","<=","≤",">",">=","≥","<>","≠"}; // note the removal of "="

m:=size(L0);
n:=size(L1);
p:={};

for j from 1 to m do
  for k from 1 to n do
    // if one of the other comparisons is found, skip to next equation
    if instring(L0(j),L1(k)) then continue(2); end;
  end;
  // now check for = symbol
  if instring(L0(j),"=") then p(0):=j; end;
end;

return(p);

end;