string.cpp File Reference

#include <Library/string.hpp>

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Functions
int	strlen (const char *s)
char *	strcat (char *dest, const char *src)
void	strcpy (char *dest, const char *src)
void	strncpy (char *dest, const char *src, size_t len)
int	strcmp (const char *s1, const char *s2)
const char *	strstr (const char *haystack, const char *needle)
void	reverse (char *s)
void	itoa (int n, char str[])
void *	memset (void *bufptr, int value, size_t size)
int	memcmp (const void *ptr1, const void *ptr2, size_t num)
void *	memmove (void *destptr, const void *srcptr, size_t size)
void *	memcpy (void *dstptr, const void *srcptr, size_t size)

Detailed Description

Standard string and memory utility library.

Author

Keeton Feavel (keeto.nosp@m.nfea.nosp@m.vel@c.nosp@m.edar.nosp@m.ville.nosp@m..edu)

Version

0.3

Date

2020-06-17

Copyright

Copyright the Xyris Contributors (c) 2020

Definition in file string.cpp.

Function Documentation

itoa()

void itoa	(	int	n,
		char	str[]
	)

Converts an integer into its ASCII representation. (This does not have a standard, ANSI implementation.)

Parameters

n	Number to be converted to ASCII
str	Buffer to hold result

Definition at line 89 of file string.cpp.

{
    int i, sign;
    if ((sign = n) < 0)
        n = -n;
    i = 0;
    do {
        str[i++] = (char)(n % 10 + (int)'0');
    } while ((n /= 10) > 0);
 
    if (sign < 0)
        str[i++] = '-';
    str[i] = '\0';
 
    reverse(str);
}

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memcmp()

int memcmp	(	const void *	ptr1,
		const void *	ptr2,
		size_t	num
	)

Compares a given number of bytes in memory at pointer A to pointer B.

Parameters

ptr1	Source pointer
ptr2	Destination pointer
num	Number of bytes

Returns

int Returns 0 if identical. If negative, pointer A is less than than pointer B and vice versa for positive.

Definition at line 114 of file string.cpp.

{
    const unsigned char* a = (const unsigned char*)ptr1;
    const unsigned char* b = (const unsigned char*)ptr2;
    for (size_t i = 0; i < num; i++) {
        if (a[i] < b[i])
            return (int)-i;
        else if (a[i] > b[i])
            return (int)i;
    }
    return 0;
}

memcpy()

void* memcpy	(	void *	dstptr,
		const void *	srcptr,
		size_t	size
	)

Parameters

dstptr
srcptr
size

Returns

void*

Definition at line 141 of file string.cpp.

{
    unsigned char* dst = (unsigned char*)dstptr;
    const unsigned char* src = (const unsigned char*)srcptr;
    for (size_t i = 0; i < size; i++)
        dst[i] = src[i];
    return dstptr;
}

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memmove()

void* memmove	(	void *	destination,
		const void *	source,
		size_t	size
	)

Moves a given number of bytes from the source to the destination.

Parameters

destination	Destination pointer
source	Source pointer
size	Number of bytes

Returns

void* Pointer to the destination

Definition at line 127 of file string.cpp.

{
    unsigned char* dst = (unsigned char*)destptr;
    const unsigned char* src = (const unsigned char*)srcptr;
    if (dst < src) {
        for (size_t i = 0; i < size; i++)
            dst[i] = src[i];
    } else {
        for (size_t i = size; i != 0; i--)
            dst[i - 1] = src[i - 1];
    }
    return destptr;
}

memset()

void* memset	(	void *	bufptr,
		int	value,
		size_t	num
	)

Sets the number of bytes in memory at ptr to the value.

Parameters

bufptr	Pointer to location in memory
value	Value to be written in memory
num	Number of bytes

Returns

void* Pointer to location in memory

Definition at line 106 of file string.cpp.

{
    unsigned char* buf = (unsigned char*)bufptr;
    for (size_t i = 0; i < size; i++)
        buf[i] = (unsigned char)value;
    return bufptr;
}

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reverse()

void reverse

(

char *

s

)

Reverses the inputted string.

Parameters

s	String to be reversed

Definition at line 78 of file string.cpp.

{
    int c;
    int j = strlen(s) - 1;
    for (int i = 0; i < j; i++, j--) {
        c = s[i];
        s[i] = s[j];
        s[j] = (char)c;
    }
}

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strcat()

char* strcat	(	char *	dest,
		const char *	src
	)

Concatanates source onto destination.

Parameters

dest	Destination
src	Source

Returns

char* Pointer to destination

Definition at line 23 of file string.cpp.

{
    const size_t len_dest = strlen(dest);
    const size_t len_src = strlen(src);
    memcpy(dest + len_dest, src, len_src + 1);
    return dest;
}

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strcmp()

int strcmp	(	const char *	s1,
		const char *	s2
	)

Compares two strings.

Parameters

s1	String one
s2	String two

Returns

int Returns a negative value if a value in s1 is less than s2, a positive number in the inverse case, and zero if both string match.

Definition at line 51 of file string.cpp.

{
    while (*s1)
    {
        if (*s1 != *s2)
            break;
 
        s1++;
        s2++;
    }
 
    return (int)*s1 - (int)*s2;
}

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strcpy()

void strcpy	(	char *	destination,
		const char *	source
	)

Copys a string from the source to the destination.

Parameters

source	String to be copied
destination	Location where string will be copied

Definition at line 31 of file string.cpp.

{
    while (*src) {
        *dest = *src;
        dest++;
        src++;
    }
    *dest = '\0';
}

strlen()

int strlen

(

const char *

s

)

Returns the length of a string.

Parameters

s	Input string

Returns

int Length of string

Definition at line 14 of file string.cpp.

{
    int i = 0;
    while (s[i] != '\0') {
        ++i;
    }
    return i;
}

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strncpy()

void strncpy	(	char *	destination,
		const char *	source,
		size_t	len
	)

Copys a string from the source to the destination.

Parameters

source	String to be copied
destination	Location where string will be copied
len	Maximum string length

Definition at line 41 of file string.cpp.

{
    while (*src && len--) {
        *dest = *src;
        dest++;
        src++;
    }
    *dest = '\0';
}

strstr()

const char* strstr	(	const char *	haystack,
		const char *	needle
	)

Locates a substring (needle) within a containing string (haystack)

Parameters

haystack	String to be searched
needle	Substring to be located

Returns

char* Pointer to the beginning of the substring

Definition at line 65 of file string.cpp.

{
    while (*haystack)
    {
        if ((*haystack == *needle) && (strcmp(haystack, needle) == 0)) {
            return haystack;
        }
        haystack++;
    }
 
    return NULL;
}

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