Linear equation, incompatible types BOOLEAN/LONGINT
I've got exercise about linear equation in Pascal and I've created simple code for comparison input numbers but when I try to run it. I have problem about incompatible types, got BOOLEAN and expected LONGINT.
program LinearEquation;
var
a, b: real;
begin
readln(a, b);
if (b = 0 and a = 0) then
writeln('INFINITY')
else if (b = 0 and a <> 0) then
writeln(1)
else if (a = 0 and b <> 0) then
writeln(0)
else if(b mod a = 0) then
writeln(1);
readln;
end.
and
13 / 9 rownan~1.pas
Error: Incompatible types: got "BOOLEAN" expected "LONGINT"
15 / 14 rownan~1.pas
Error: Incompatible types: got "BOOLEAN" expected "LONGINT"
17 / 14 rownan~1.pas
Error: Incompatible types: got "BOOLEAN" expected "LONGINT"
17 / 14 rownan~1.pas
Error: Incompatible types: got "BOOLEAN" expected "LONGINT"
pascal operator-precedence
edited Nov 23 '18 at 11:51
Andreas Rejbrand
72.4k6208302
asked Nov 23 '18 at 10:45
Rav3Rav3
559
add a comment |
I've got exercise about linear equation in Pascal and I've created simple code for comparison input numbers but when I try to run it. I have problem about incompatible types, got BOOLEAN and expected LONGINT.
program LinearEquation;
var
a, b: real;
begin
readln(a, b);
if (b = 0 and a = 0) then
writeln('INFINITY')
else if (b = 0 and a <> 0) then
writeln(1)
else if (a = 0 and b <> 0) then
writeln(0)
else if(b mod a = 0) then
writeln(1);
readln;
end.
and
13 / 9 rownan~1.pas
Error: Incompatible types: got "BOOLEAN" expected "LONGINT"
15 / 14 rownan~1.pas
Error: Incompatible types: got "BOOLEAN" expected "LONGINT"
17 / 14 rownan~1.pas
Error: Incompatible types: got "BOOLEAN" expected "LONGINT"
17 / 14 rownan~1.pas
Error: Incompatible types: got "BOOLEAN" expected "LONGINT"
pascal operator-precedence
edited Nov 23 '18 at 11:51
Andreas Rejbrand
72.4k6208302
asked Nov 23 '18 at 10:45
Rav3Rav3
559
2
Read up about the precedence of operators, or just add more (). The rules for operator precedence vary with languages. Note that the outer () in if statements are redundant in Pascal.
– Marco van de Voort
Nov 23 '18 at 10:55
1
...in other words, you wantif (b=0) and (a=0) ...
– linuxfan
Nov 23 '18 at 14:18
add a comment |
I've got exercise about linear equation in Pascal and I've created simple code for comparison input numbers but when I try to run it. I have problem about incompatible types, got BOOLEAN and expected LONGINT.
program LinearEquation;
var
a, b: real;
begin
readln(a, b);
if (b = 0 and a = 0) then
writeln('INFINITY')
else if (b = 0 and a <> 0) then
writeln(1)
else if (a = 0 and b <> 0) then
writeln(0)
else if(b mod a = 0) then
writeln(1);
readln;
end.
and
13 / 9 rownan~1.pas
Error: Incompatible types: got "BOOLEAN" expected "LONGINT"
15 / 14 rownan~1.pas
Error: Incompatible types: got "BOOLEAN" expected "LONGINT"
17 / 14 rownan~1.pas
Error: Incompatible types: got "BOOLEAN" expected "LONGINT"
17 / 14 rownan~1.pas
Error: Incompatible types: got "BOOLEAN" expected "LONGINT"
pascal operator-precedence
edited Nov 23 '18 at 11:51
Andreas Rejbrand
72.4k6208302
asked Nov 23 '18 at 10:45
Rav3Rav3
559
I've got exercise about linear equation in Pascal and I've created simple code for comparison input numbers but when I try to run it. I have problem about incompatible types, got BOOLEAN and expected LONGINT.
program LinearEquation;
var
a, b: real;
begin
readln(a, b);
if (b = 0 and a = 0) then
writeln('INFINITY')
else if (b = 0 and a <> 0) then
writeln(1)
else if (a = 0 and b <> 0) then
writeln(0)
else if(b mod a = 0) then
writeln(1);
readln;
end.
and
13 / 9 rownan~1.pas
Error: Incompatible types: got "BOOLEAN" expected "LONGINT"
15 / 14 rownan~1.pas
Error: Incompatible types: got "BOOLEAN" expected "LONGINT"
17 / 14 rownan~1.pas
Error: Incompatible types: got "BOOLEAN" expected "LONGINT"
17 / 14 rownan~1.pas
Error: Incompatible types: got "BOOLEAN" expected "LONGINT"
pascal operator-precedence
pascal operator-precedence
edited Nov 23 '18 at 11:51
Andreas Rejbrand
72.4k6208302
asked Nov 23 '18 at 10:45
Rav3Rav3
559
edited Nov 23 '18 at 11:51
Andreas Rejbrand
72.4k6208302
asked Nov 23 '18 at 10:45
Rav3Rav3
559
edited Nov 23 '18 at 11:51
Andreas Rejbrand
72.4k6208302
edited Nov 23 '18 at 11:51
Andreas Rejbrand
72.4k6208302
edited Nov 23 '18 at 11:51
Andreas Rejbrand
72.4k6208302
72.4k6208302
asked Nov 23 '18 at 10:45
Rav3Rav3
559
asked Nov 23 '18 at 10:45
Rav3Rav3
559
asked Nov 23 '18 at 10:45
Rav3Rav3
559
559
2
Read up about the precedence of operators, or just add more (). The rules for operator precedence vary with languages. Note that the outer () in if statements are redundant in Pascal.
– Marco van de Voort
Nov 23 '18 at 10:55
1
...in other words, you wantif (b=0) and (a=0) ...
– linuxfan
Nov 23 '18 at 14:18
add a comment |
2
Read up about the precedence of operators, or just add more (). The rules for operator precedence vary with languages. Note that the outer () in if statements are redundant in Pascal.
– Marco van de Voort
Nov 23 '18 at 10:55
1
...in other words, you wantif (b=0) and (a=0) ...
– linuxfan
Nov 23 '18 at 14:18
2
2
Read up about the precedence of operators, or just add more (). The rules for operator precedence vary with languages. Note that the outer () in if statements are redundant in Pascal.
– Marco van de Voort
Nov 23 '18 at 10:55
Read up about the precedence of operators, or just add more (). The rules for operator precedence vary with languages. Note that the outer () in if statements are redundant in Pascal.
– Marco van de Voort
Nov 23 '18 at 10:55
1
1
...in other words, you want
if (b=0) and (a=0) ...– linuxfan
Nov 23 '18 at 14:18
...in other words, you want
if (b=0) and (a=0) ...– linuxfan
Nov 23 '18 at 14:18
add a comment |
1 Answer
1
active
oldest
votes
At least in modern Delphi, and has higher precedence than =, so
a = 0 and b = 0
is interpreted as
(a = (0 and b)) = 0.
But the and operator cannot accept an integer and a floating-point value as operands (two integers would have been OK, though). Hence the error.
Had a and b been integers, 0 and b would have been the bitwise conjunction of 0 and b, that is, 0. Thus, we would have had
(a = 0) = 0.
This reads either true = 0 (if a is equal to 0) or false = 0 (if a is different from 0). But a boolean cannot be compared to an integer, so the compiler would have complained about that.
Still, this was just an academic exercise. Clearly, your intension was
(a = 0) and (b = 0).
Just add the parentheses:
if (b = 0) and (a = 0) then
writeln('INFINITY')
answered Nov 23 '18 at 11:31
Andreas RejbrandAndreas Rejbrand
72.4k6208302
add a comment |
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1 Answer
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1 Answer
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active
oldest
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oldest
votes
active
oldest
votes
At least in modern Delphi, and has higher precedence than =, so
a = 0 and b = 0
is interpreted as
(a = (0 and b)) = 0.
But the and operator cannot accept an integer and a floating-point value as operands (two integers would have been OK, though). Hence the error.
Had a and b been integers, 0 and b would have been the bitwise conjunction of 0 and b, that is, 0. Thus, we would have had
(a = 0) = 0.
This reads either true = 0 (if a is equal to 0) or false = 0 (if a is different from 0). But a boolean cannot be compared to an integer, so the compiler would have complained about that.
Still, this was just an academic exercise. Clearly, your intension was
(a = 0) and (b = 0).
Just add the parentheses:
if (b = 0) and (a = 0) then
writeln('INFINITY')
answered Nov 23 '18 at 11:31
Andreas RejbrandAndreas Rejbrand
72.4k6208302
add a comment |
At least in modern Delphi, and has higher precedence than =, so
a = 0 and b = 0
is interpreted as
(a = (0 and b)) = 0.
But the and operator cannot accept an integer and a floating-point value as operands (two integers would have been OK, though). Hence the error.
Had a and b been integers, 0 and b would have been the bitwise conjunction of 0 and b, that is, 0. Thus, we would have had
(a = 0) = 0.
This reads either true = 0 (if a is equal to 0) or false = 0 (if a is different from 0). But a boolean cannot be compared to an integer, so the compiler would have complained about that.
Still, this was just an academic exercise. Clearly, your intension was
(a = 0) and (b = 0).
Just add the parentheses:
if (b = 0) and (a = 0) then
writeln('INFINITY')
answered Nov 23 '18 at 11:31
Andreas RejbrandAndreas Rejbrand
72.4k6208302
add a comment |
At least in modern Delphi, and has higher precedence than =, so
a = 0 and b = 0
is interpreted as
(a = (0 and b)) = 0.
But the and operator cannot accept an integer and a floating-point value as operands (two integers would have been OK, though). Hence the error.
Had a and b been integers, 0 and b would have been the bitwise conjunction of 0 and b, that is, 0. Thus, we would have had
(a = 0) = 0.
This reads either true = 0 (if a is equal to 0) or false = 0 (if a is different from 0). But a boolean cannot be compared to an integer, so the compiler would have complained about that.
Still, this was just an academic exercise. Clearly, your intension was
(a = 0) and (b = 0).
Just add the parentheses:
if (b = 0) and (a = 0) then
writeln('INFINITY')
answered Nov 23 '18 at 11:31
Andreas RejbrandAndreas Rejbrand
72.4k6208302
At least in modern Delphi, and has higher precedence than =, so
a = 0 and b = 0
is interpreted as
(a = (0 and b)) = 0.
But the and operator cannot accept an integer and a floating-point value as operands (two integers would have been OK, though). Hence the error.
Had a and b been integers, 0 and b would have been the bitwise conjunction of 0 and b, that is, 0. Thus, we would have had
(a = 0) = 0.
This reads either true = 0 (if a is equal to 0) or false = 0 (if a is different from 0). But a boolean cannot be compared to an integer, so the compiler would have complained about that.
Still, this was just an academic exercise. Clearly, your intension was
(a = 0) and (b = 0).
Just add the parentheses:
if (b = 0) and (a = 0) then
writeln('INFINITY')
answered Nov 23 '18 at 11:31
Andreas RejbrandAndreas Rejbrand
72.4k6208302
answered Nov 23 '18 at 11:31
Andreas RejbrandAndreas Rejbrand
72.4k6208302
answered Nov 23 '18 at 11:31
Andreas RejbrandAndreas Rejbrand
72.4k6208302
answered Nov 23 '18 at 11:31
Andreas RejbrandAndreas Rejbrand
72.4k6208302
72.4k6208302
add a comment |
add a comment |
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2
Read up about the precedence of operators, or just add more (). The rules for operator precedence vary with languages. Note that the outer () in if statements are redundant in Pascal.
– Marco van de Voort
Nov 23 '18 at 10:55
1
...in other words, you want
if (b=0) and (a=0) ...– linuxfan
Nov 23 '18 at 14:18