Synonyms & Antonyms of overflow (Entry 1 of 2) 1 a great flow of water or of something that overwhelms a great overflow of water from the heavy rains swept mud and silt down onto the highway. Overflow definition, to flow or run over, as rivers or water: After the thaw, the river overflows and causes great damage.
The CSS overflow property controls what happens to content that is too big to fit into an area.
This text is really long and the height of its container is only 100 pixels. Therefore, a scrollbar is added to help the reader to scroll the content. Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat. Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper suscipit lobortis nisl ut aliquip ex ea commodo consequat. Duis autem vel eum iriure dolor in hendrerit in vulputate velit esse molestie consequat, vel illum dolore eu feugiat nulla facilisis at vero eros et accumsan et iusto odio dignissim qui blandit praesent luptatum zzril delenit augue duis dolore te feugait nulla facilisi. Nam liber tempor cum soluta nobis eleifend option congue nihil imperdiet doming id quod mazim placerat facer possim assum. Typi non habent claritatem insitam; est usus legentis in iis qui facit eorum claritatem.
Try it Yourself »
CSS Overflow
The overflow property specifies whether to clip the content or to add scrollbars when the content of an element is too big to fit in the specified area.
The overflow property has the following values:
visible- Default. The overflow is not clipped. The content renders outside the element's boxhidden- The overflow is clipped, and the rest of the content will be invisiblescroll- The overflow is clipped, and a scrollbar is added to see the rest of the contentauto- Similar toscroll, but it adds scrollbars only when necessary
Note: The overflow property only works for block elements with a specified height.
Note: In OS X Lion (on Mac), scrollbars are hidden by default and only shown when being used (even though 'overflow:scroll' is set).
overflow: visible
By default, the overflow is visible, meaning that it is not clipped and it renders outside the element's box:
You can use the overflow property when you want to have better control of the layout. The overflow property specifies what happens if content overflows an element's box.
Example
div {
width: 200px;
height: 50px;
background-color: #eee;
overflow: visible;
}
Try it Yourself »width: 200px;
height: 50px;
background-color: #eee;
overflow: visible;
}
overflow: hidden
With the hidden value, the overflow is clipped, and the rest of the content is hidden:
You can use the overflow property when you want to have better control of the layout. The overflow property specifies what happens if content overflows an element's box.
Example
Try it Yourself »overflow: scroll
Setting the value to scroll, the overflow is clipped and a scrollbar is added to scroll inside the box. Note that this will add a scrollbar both horizontally and vertically (even if you do not need it):
You can use the overflow property when you want to have better control of the layout. The overflow property specifies what happens if content overflows an element's box.
Example
Try it Yourself »overflow: auto
The auto value is similar to scroll, but it adds scrollbars only when necessary:
You can use the overflow property when you want to have better control of the layout. The overflow property specifies what happens if content overflows an element's box.
Example
Try it Yourself »overflow-x and overflow-y
The overflow-x and overflow-y properties specifies whether to change the overflow of content just horizontally or vertically (or both):
overflow-x specifies what to do with the left/right edges of the content.overflow-y specifies what to do with the top/bottom edges of the content.
You can use the overflow property when you want to have better control of the layout. The overflow property specifies what happens if content overflows an element's box.
Overflow Ep 1
Example
Overflow Anime
div {
overflow-x: hidden; /* Hide horizontal scrollbar */
overflow-y: scroll; /* Add vertical scrollbar */
}
Try it Yourself »overflow-x: hidden; /* Hide horizontal scrollbar */
overflow-y: scroll; /* Add vertical scrollbar */
}
Test Yourself with Exercises!
Overflow Characters
All CSS Overflow Properties
| Property | Description |
|---|---|
| overflow | Specifies what happens if content overflows an element's box |
| overflow-x | Specifies what to do with the left/right edges of the content if it overflows the element's content area |
| overflow-y | Specifies what to do with the top/bottom edges of the content if it overflows the element's content area |
Overflow is a phenomenon where operations on 2 numbers exceeds the maximum (or goes below the minimum) value the data type can have. Usually it is thought that integral types are very large and people don't take into account the fact that sum of two numbers can be larger than the range. But in things like scientific and mathematical computation, this can happen. For example, an unhandled arithmetic overflow in the engine steering software was the primary cause of the crash of the maiden flight of the Ariane 5 rocket. The software had been considered bug-free since it had been used in many previous flights; but those used smaller rockets which generated smaller accelerations than Ariane 5's.This article will tell how this problem can be tackled.
In this article, we will only deal with integral types (and not with types like float and double)
In order to understand how to tackle this problem we will first know how numbers are stored.
If the size of a data type is n bytes, it can store 28n different values. This is called the data type's range.
If size of an unsigned data type is n bytes, it ranges from 0 to 28n-1
If size of a signed data type is n bytes, it ranges from -28n-1 to 28n-1-1
So, a short(usually 2 bytes) ranges from -32768 to 32767 and an unsigned short ranges from 0 to 65535
Consider a short variable having a value of 250.
It is stored int the computer like this (in binary format)
00000000 11111010
Complement of a number is a number with its bits toggled. It is denoted by ~
For eg. ~250 is 11111111 00000101
Negative numbers are stored using 2's complement system. According to this system, -n=~n+1
-250 is stored as 11111111 00000110
http://stackoverflow.com/questions/1049722/what-is-2s-complement
10000000 00000000 (-32768) has no positive counterpart. Its negative is the number itself (try -n=~n+1)
11100010 01110101 will be read as 57973 if data type is unsigned while it will be read as -7563 if data type is signed. If you add 65536 (which is the range) to -7563, you get 57973.
Overflow:
Consider a data type var_t of 1 byte (range is 256):
signed var_t a,b;
unsigned var_t c,d;
If c is 200(11001000) and d is 100(01100100), c+d is 300(00000001 00101100), which is more than the max value 255(11111111). 00000001 00101100 is more than a byte, so the higher byte will be rejected and c+d will be read as 44. So, 200+100=44! This is absurd! (Note that 44=300-256). This is an example of an unsigned overflow, where the value couldn't be stored in the available no. of bytes. In such overflows, the result is moduloed by range (here, 256).
If a is 100(01100100) and b is 50(00110010), a+b is 150(10010110), which is more than the max value 127. Instead, a+b will be read as -106 (note that -106=150-256). This is an example of a signed overflow, where result is moduloed by range(here, 256).
Division and modulo can never generate an overflow.
Addition overflow:
Overflow can only occur when sign of numbers being added is the same (which will always be the case in unsigned numbers)
signed overflow can be easily detected by seeing that its sign is opposite to that of the operands.
Let us analyze overflow in unsigned integer addition.
Consider 2 variables a and b of a data type with size n and range R.
Let + be actual mathematical addition and a$b be the addition that the computer does.
If a+b<=R-1, a$b=a+b
As a and b are unsigned, a$b is more or equal to than both a and b.
If a+b>=R a$b=a+b-R
as R is more than both a and b, a-R and b-R are negative
So, a+b-R<a and a+b-R<b
Therefore, a$b is less than both a and b.
This difference can be used to detect unsigned addition overflow. a-b can be treated as a+(-b) hence subtraction can be taken care of in the same way.
Multiplication overflow:There are two ways to detect an overflow:
1. if a*b>max, then a>max/b (max is R-1 if unsigned and R/2-1 if signed).
2. Let there be a data type of size n and range R called var_t and a data type of size 2n called var2_t.
Let there be 2 variables of var_t called a and b. Range of var2_t will be R*R, which will always be more than the product of a and b. hence if var2_t(a)*var2_t(b)>R overflow has happened.
Truncation:This happens when a shorter is assigned from a longer variable. For eg,
Similar behaviour will be shown if int is replaced by unsigned short.
Type conversion:consider
Whenever an operation is performed between an unsigned and a signed variable of the same type, operands are converted to unsigned.
Whenever an operation is performed between a long type and a short type, operands are converted to the long type.
The above code returned 1 as a and b were converted to unsigned int and then compared.
If we used __int64 (a 64-bit type) instead of unsigned int and 18446744073709551610 instead of 4294967290, the result would have been the same.
Type promotion:Whenever an operation is performed on two variables of a type shorter than int, the type of both variables is converted to int. For eg.
In this article, we will only deal with integral types (and not with types like float and double)
In order to understand how to tackle this problem we will first know how numbers are stored.
About integers:
If the size of a data type is n bytes, it can store 28n different values. This is called the data type's range.
If size of an unsigned data type is n bytes, it ranges from 0 to 28n-1
If size of a signed data type is n bytes, it ranges from -28n-1 to 28n-1-1
So, a short(usually 2 bytes) ranges from -32768 to 32767 and an unsigned short ranges from 0 to 65535
Consider a short variable having a value of 250.
It is stored int the computer like this (in binary format)
00000000 11111010
Complement of a number is a number with its bits toggled. It is denoted by ~
For eg. ~250 is 11111111 00000101
Negative numbers are stored using 2's complement system. According to this system, -n=~n+1
-250 is stored as 11111111 00000110
http://stackoverflow.com/questions/1049722/what-is-2s-complement
10000000 00000000 (-32768) has no positive counterpart. Its negative is the number itself (try -n=~n+1)
11100010 01110101 will be read as 57973 if data type is unsigned while it will be read as -7563 if data type is signed. If you add 65536 (which is the range) to -7563, you get 57973.
Overflow:
Consider a data type var_t of 1 byte (range is 256):
signed var_t a,b;
unsigned var_t c,d;
If c is 200(11001000) and d is 100(01100100), c+d is 300(00000001 00101100), which is more than the max value 255(11111111). 00000001 00101100 is more than a byte, so the higher byte will be rejected and c+d will be read as 44. So, 200+100=44! This is absurd! (Note that 44=300-256). This is an example of an unsigned overflow, where the value couldn't be stored in the available no. of bytes. In such overflows, the result is moduloed by range (here, 256).
If a is 100(01100100) and b is 50(00110010), a+b is 150(10010110), which is more than the max value 127. Instead, a+b will be read as -106 (note that -106=150-256). This is an example of a signed overflow, where result is moduloed by range(here, 256).
Detecting overflow:
Division and modulo can never generate an overflow.
Addition overflow:
Overflow can only occur when sign of numbers being added is the same (which will always be the case in unsigned numbers)
signed overflow can be easily detected by seeing that its sign is opposite to that of the operands.
Let us analyze overflow in unsigned integer addition.
Consider 2 variables a and b of a data type with size n and range R.
Let + be actual mathematical addition and a$b be the addition that the computer does.
If a+b<=R-1, a$b=a+b
As a and b are unsigned, a$b is more or equal to than both a and b.
If a+b>=R a$b=a+b-R
as R is more than both a and b, a-R and b-R are negative
So, a+b-R<a and a+b-R<b
Therefore, a$b is less than both a and b.
This difference can be used to detect unsigned addition overflow. a-b can be treated as a+(-b) hence subtraction can be taken care of in the same way.
Multiplication overflow:There are two ways to detect an overflow:
1. if a*b>max, then a>max/b (max is R-1 if unsigned and R/2-1 if signed).
2. Let there be a data type of size n and range R called var_t and a data type of size 2n called var2_t.
Let there be 2 variables of var_t called a and b. Range of var2_t will be R*R, which will always be more than the product of a and b. hence if var2_t(a)*var2_t(b)>R overflow has happened.
Truncation:This happens when a shorter is assigned from a longer variable. For eg,
short a;long b=70000;a=b;Only the lower bits are copied and the value's meaning is translated.short a;int b=57973;a=b; will also show this behaviour become -7563.Similar behaviour will be shown if int is replaced by unsigned short.
Type conversion:consider
unsignedint a=4294967290;int b=-6; return (ab);This returns 1.Whenever an operation is performed between an unsigned and a signed variable of the same type, operands are converted to unsigned.
Whenever an operation is performed between a long type and a short type, operands are converted to the long type.
The above code returned 1 as a and b were converted to unsigned int and then compared.
If we used __int64 (a 64-bit type) instead of unsigned int and 18446744073709551610 instead of 4294967290, the result would have been the same.
Type promotion:Whenever an operation is performed on two variables of a type shorter than int, the type of both variables is converted to int. For eg.
short a=32000,b=32000;cout<<a+b<<endl; would display 64000, which is more than the max value of short. The reason is that a and b were converted to int and a+b would return an int, which can have a value of 64000.Libraries:
Microsoft Visual C++ 2010 has a header file safeint.h which has functions like safeadd,safesubtract,etc. It is a templated header file (and hence header only).