C Reference function rand() generate a random number

This function of stdlib will generate a random number.

Usage of rand():

int rand (void);

Parameters:

The function rand() returns a pseudo-random integral number.
This number will be in the range 0 to RAND_MAX. The algorithm of rand() uses a seed to generate the series of numbers, this is why srand must be used to initialize the seed to some distinctive value.

The constant RAND_MAX is defined in standard library (stdlib). More »


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C Reference function strtol()

This function of stdlib will convert a string to long integer.

Usage of strtol():

long int strtol ( const char * str, char ** endptr, int base );

Parameters:

C string str interpreting its content as an integral number of the specified base, which is returned as a long int value. If endptr is not a null pointer, the function also sets the value pointed by endptr to point to the first character after the number. White-spaces are discarded until the first non-whitespace character is found. More »


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C Reference function strtoul()

This function of stdlib will convert a string to an unsigned long integer.

Usage of strtoul():

unsigned long int strtoul ( const char * str, char ** endptr, int base );

Parameters:

C string str interpreting its content as an unsigned integral number of the specified base, which is returned as an unsigned long int value. More »


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C Reference function atoi() convert a string to an integer

This function of stdlib will convert a string to an integer.

Usage of atoi():

int atoi ( const char * str );

Parameters:

C string str interpreting its content as a integer. White-spaces are discarded until the first non-whitespace character is found.

Return value:

The function returns the converted integral number as an int value, if successful. If no valid conversion could be performed then an zero value is returned. If the value is out of range then INT_MAX or INT_MIN is returned. More »


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C Reference function atof() convert a string to a double

This function of stdlib will convert a string to a double.

Usage of atof():

double atof ( const char * str );

Parameters:

C string str interpreting its content as a floating point number. White-spaces are discarded until the first non-whitespace character is found. A valid floating point number for atof is formed by: plus or minus sign, sequence of digits, decimal point and optional exponent part (character ‘e’ or ‘E’) More »


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C Reference function atol()

This function of stdlib will convert a string to a long integer.

Usage of atol():

long int atol ( const char * str );

Parameters:

C string str interpreting its content as a integer. White-spaces are discarded until the first non-whitespace character is found.

Return value:

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C Reference function labs()

This function will return the absolute value of a long integer.

Usage of labs():

long int labs (long int n);

Parameters:

An integer n.

Return value:

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C Reference function ldiv()

The integral quotient and remainder of the division of numerator by denominator integer n,d

Usage of ldiv():

ldiv_t ldiv ( long int n, long int d );

Parameters:

n = numerator

d = denominator

Return value:

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C Reference function div()

This function of stdlib.h will return the quotient and remainder of the division of numerator by denominator integers n,d.

Usage of div():

div_t div ( int n, int d );

Parameters:

n = numerator

d = denominator

Return value:

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C Reference function abs()

This function of stdlib will return the absolute value of an integer.

Usage of abs():

int abs ( int x );

Parameters:

An integer x.

Return value:

The absolute value of integer x.

Source code example of abs():

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