C floating point to integer 5, C floating point to integer

This should be a matter of data structure.

In k&rc, the float value is automatically converted to a double type before being used in an expression or as a parameter. ANSI C generally does not automatically convert floats to doubles. Some programs have assumed that the float argument will be converted to double, and in order to protect the large number of such programs, all the float arguments of the printf() function are automatically converted to double.

As long as you enter the range of the float, then after converting to double, the lower part of the binary (that is, the later part) of this data in memory is 0. And this data is put into the stack, so when reading in %d format, only the next 4 bytes of data are read, so the occurrence is 0, you try to input a few more decimal places, such as input, etc., the value is not 0, it is a big number, it is likely to be negative.

According to your program, variable b is not used, and the data type of a has not changed, a=static cast assigns a floating-point variable to an integer variable and is still an integer variable.

printf("%d",ftemp);The output type is incorrect, it should be %f

printf does not automatically convert the type when it outputs. You must cast (int)ftemp manually

What you're asking should be why use printf("%d",ftemp), no matter what number is input, it always outputs 0, right?

I don't know about this, I changed ftemp to a specific floating-point number, he doesn't output zeros, I don't know how he calculated.

In C, floating-point conversion to integer can be used forcibly-typed or auto-typed, for example: (int) a = .

1. Forced type conversion.

Forced type conversion is achieved through type conversion operations. Its general form is: (type specifier) (expression), and its function is to cast the result of the expression into the type represented by the type specifier.

For example: (double) a converts a to a double, and (int)(x+y) converts the result of x+y to an integer.

2. Automatic type conversion.

1) When performing arithmetic operations, the low type (short byte) can be converted to the high type (long byte); For example: int type to double type, char type to int type, etc.

2) In the assignment expression, the type of the value of the expression on the right side of the equal sign is automatically and implicitly converted to the type of the variable on the left, and the value is assigned to it.

3) When the function is called, the value of the argument is passed to the parameter, and the system will first implicitly convert the value type of the argument to the type of the parameter, and then assign the value to the parameter.

4) When a function has a return value, the system will first implicitly convert the value type of the returned expression to the return type of the function, and then assign the value to the calling function return.

An integer, a basic term used in computers, refers to data that has no decimal parts. Integers can be specified with decimal, hexadecimal or octal symbols, and can be preceded by optional symbols (- or +) including integer constants and integer variables, which in turn include short integers, basic integers, and long integers, which are divided into signed and unsigned versions, which is an intelligent way of calculation.

Character types include character constants and character variables. A string constant is a sequence of characters enclosed in a pair of double quotation marks. The value of a character variable is a character constant, that is, a single character.

The type specifier for character variables is char. The format and writing rules for character variable type descriptions are the same as those for integer variables.

Floating-point uses exponents to allow the position of the decimal point to fluctuate up or down as needed, giving it the flexibility to express a wider range of real numbers.

This data type is similar to the single-precision data type (float), but the accuracy is higher than float, and the memory space occupied by compilation varies according to different compilers, which is a variable type that represents real variables in C C++.

An integer int can be understood as an integer char, which means that you are not entering a number.

A float is a number with a decimal point.

Double is a little more decimal place.

Integer: A simple integer (divided into short, unsigned, int, long).

Instances: 1545, -4444, -979

Character: Represents characters (divided into char, unsigned char).

Examples: a, b, c, d

Floating-point type Double-precision floating-point type: Represents decimals (double-precision is more accurate) (divided into double, float, long float, long double).

Example: ,

char character, which occupies 1 byte.

short integer, which occupies 2 bytes.

int integer, which occupies 4 bytes.

long is a long integer, accounting for 4 bytes.

The preceding data is integer data and cannot contain decimal points.

The following is the real data, with decimal points.

float single-precision floating-point type, which occupies 4 bytes.

double, 8 bytes.

Sort from smallest to largest: char character type e.g'a' 'b'and so on, note that it has to be single-quoted for one byte. int is an ordinary number, such as 123 33, the specific size depends on the compiler, usually two or four bytes.

Long long integer, as the name suggests, is an integer extended version, and the byte size is greater than int. float single-precision real numbers, which you can simply understand as decimals, include double-precision real numbers, which are the extended version of single-precision and occupy the largest number of bytes. For specific use, please refer to the corresponding manual.

In the C language, data types are divided into integer, solid and pointer types (the following are all represented in 32-bit operating systems): where integers are divided into char, short int , long int , long long, various types of use, can be preceded by unsigned to represent the unsigned char character type, the size of the representation is -128 127, the size is one byte, where 0 - 127 is coded as asc code short int short int - 65536 65535 2 bytes long int Shaping - More than 2 billion More than 2 billion 4 bytes long long long 8 bytes long int is usually written as int represents the word length of the CPU, and the word length of the CPU in the operating system is 32 bits, that is, 4 bytes Implementation (floating-point) is divided into float and double: float 6 7 significant digits 4 bytes double 15 16 significant digits 8 bytes In modern CPUs, There is a coprocessor that specializes in the operation of floating-point numbers, and then intercepts the precision of the pointer type 32-bit unsigned integer according to the type of pointer, i.e. unsigned int, but it can only represent the numbered space of one bit in memoryNote:

The memory addressing range of a 32-bit CPU is from 32 zeros to 32 1s, for a total of 4 GB, so a 32-bit operating system only supports up to 4 GB of memory.

Here's LZ to see for yourself.

There are several ways to round the C language:

1. Assign values directly to integer variables. Such as:

int i = ;or i = (int);

This method uses the decimal part to be used for your problem.

2. The integer division operator " " in C C++ itself has an integer function (int int), and the return value of the integer function introduced below is double. Integer division rounds off the decimal part of a positive number and can be used for your problem. However, the integer division of negative numbers depends on the C compiler used.

3. Use the floor function. floor(x) returns the largest integer less than or equal to x. Such as:

floor( = 2

floor( = -3

4. Use the ceil function. Ceil(x) returns the smallest integer greater than x. Such as:

ceil( = 3

ceil( = -2

floor() is rounded to negative infinity, floor( = -3;ceil() is rounded to positive infinity, and ceil( = function can be used for your problem.

5、int b = (int)a;int c = (int)(a+; Round.

There is no rounding in the C language, and when converting a floating-point type to an integer, only the value before the decimal point is retained.

float ftemp;

Don't follow =0;Because once you've assigned a value to ftemp, it's not a way to write via the keyboard.

allowed, because the space is already occupied. This is not an assignment of expressions like a=b+c.

Dizzy, do you want me to give you the source ** and you copy it directly?

That's up to you!

#include

void main()

Enter a random number, hit enter, and see the results.

Conversion can be done automatically through a forced type conversion or during the assignment process.

Cast type conversion. C provides a coercive type converter, which can be represented as (type), which has a right-to-left conjunctive type, and the usage example is "(type) variable", then the corresponding variable is converted to the type in parentheses, so when you want to convert a floating-point type to an integer, you can use int in parentheses:

If you assign a floating-point variable directly to an integer, it will be automatically converted to an integer:

Note, however, that when a float variable is converted to an integer, the decimal part is discarded, but it does not follow the principle of rounding, and if the value of the floating-point type is too large to exceed the range that the integer can hold, the result is inconclusive.

The method of converting an unsigned integer to a float in C is as follows:

unsigned

intx=123;

1. Output casting, such as:

printf("%f",x

This output is abnormal because %f is of different types from x.

printf("%f"Chang companion type, float)x casts to floating-point type, and the output is correct.

2. Store in the corresponding variables, such as:

floatfval;

fval=x

The system implicitly converts.

Since the maximum number of floats is 7 digits, not all integers can be represented by float variables, so it is best to use the double type to store arbitrary integers.

printf("%f",fval

The output is normal. double

dval;dval=x

The system implicitly converts.

printf("%f",dval

The output is normal.

The value range of the signed char is -128 127, but how can the ASCII code of the character not have a negative number? Make up a field by yourself and see if there is one.,Convert integers (positive and negative) to character type,I only know that there are 255 character values.,I don't remember what character is the spine of the hand! There are some characters that are not printable, you have to know this thing...

Bi Burn. As for unsignedchar, let's make it up too, and remember to use unsigned characters.

One of the simplest examples of conversion, I hope that rolling shirts can help you.

#include

voidmain()inta;

scanf("%d",&a);

printf("%f",(float)a);