replace.c

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#include <ctype.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
 
#include "replace.h"
#include "strstri.h"
 
// replace_chr()
void replace_chr(char* s, char c1, char c2)
{
    if (s != NULL && c1 != '\0')
    {
        size_t length = strlen(s);
        if (c2 != '\0')
        {
            for (size_t index = 0; index < length; index++)
            {
                if (s[index] == c1)
                {
                    s[index] = c2;
                }
            }
        }
        else
        {
            size_t writeIndex = 0;
            for (size_t readIndex = 0; readIndex < length; readIndex++)
            {
                if (s[readIndex] != c1)
                {
                    s[writeIndex] = s[readIndex];
                    writeIndex++;
                }
            }
            s[writeIndex] = '\0';
        }
    }
}
 
// replace_chri()
void replace_chri(char* s, char c1, char c2)
{
    if (s != NULL && c1 != '\0')
    {
        size_t length = strlen(s);
        int upperc1 = toupper(c1);
        if (c2 != '\0')
        {
            for (size_t index = 0; index < length; index++)
            {
                if (toupper(s[index]) == upperc1)
                {
                    s[index] = c2;
                }
            }
        }
        else
        {
            size_t writeIndex = 0;
            for (size_t readIndex = 0; readIndex < length; readIndex++)
            {
                if (toupper(s[readIndex]) != upperc1)
                {
                    s[writeIndex] = s[readIndex];
                    writeIndex++;
                }
            }
            s[writeIndex] = '\0';
        }
    }
}
 
static void _append_range(char** buffer, const char* start, const char* end)
{
    if (buffer != NULL && start < end)
    {
        size_t charsToCopy = end - start;
        char* text = *buffer;
        if (text == NULL)
        {
            text = malloc(charsToCopy + 1);
            if (text != NULL)
            {
                memcpy(text, start, charsToCopy);
                text[charsToCopy] = '\0';
                *buffer = text;
            }
        }
        else
        {
            size_t currentLength = strlen(text);
            char* reallocText = realloc(text, currentLength + charsToCopy + 1);
            if (reallocText != NULL)
            {
                memcpy(reallocText + currentLength, start, charsToCopy);
                reallocText[currentLength + charsToCopy] = '\0';
                *buffer = reallocText;
            }
        }
    }
}
 
 
// replace_str()
char* replace_str(const char* s, const char* str1, const char* str2)
{
    char* newText = NULL;
    if (s != NULL && str1 != NULL && str2 != NULL)
    {
        size_t length = strlen(s);
        size_t str1Length = strlen(str1);
        size_t str2Length = strlen(str2);
        const char* start = s;
        const char* end = start + length;
        while (start < end)
        {
            const char* found = strstr(start, str1);
            if (found != NULL)
            {
                _append_range(&newText, start, found);
                if (str2Length > 0)
                {
                    _append_range(&newText, str2, str2 + str2Length);
                }
                start = found + str1Length;
            }
            else
            {
                _append_range(&newText, start, start + strlen(start));
                start = end;
            }
        }
    }
 
    return newText;
}
 
// replace_stri()
char* replace_stri(const char* s, const char* str1, const char* str2)
{
    char* newText = NULL;
    if (s != NULL && str1 != NULL && str2 != NULL)
    {
        size_t length = strlen(s);
        size_t str1Length = strlen(str1);
        size_t str2Length = strlen(str2);
        const char* start = s;
        const char* end = start + length;
        while (start < end)
        {
            const char* found = strstri(start, str1);
            if (found != NULL)
            {
                _append_range(&newText, start, found);
                if (str2Length > 0)
                {
                    _append_range(&newText, str2, str2 + str2Length);
                }
                start = found + str1Length;
            }
            else
            {
                _append_range(&newText, start, start + strlen(start));
                start = end;
            }
        }
    }
 
    return newText;
}