replaceString | C

November 13th, 2021 05:27:44 PM

					
//===============replaceString.c=============== #include "replaceString.h" //Normally I'd make a replaceStringMalloc to return a malloced string or a replaceStringMut to change the original string, but I'm not satisfied with those function names so it's best just to do to = (char*)malloc(replaceStringLength(from, replace, replacement)); replaceString(to, from, replace, replacement); //If this was c++, I'd have no problem just overloading replaceString //Returns the length of the resulting string (minus the null char) size_t replaceStringLength(const char* from, const char* replace, const char* replacement){ size_t fromLength = strlen(from); size_t replaceLength = strlen(replace); size_t replacementLength = strlen(replacement); size_t fromEndIt = 0; size_t toLength = 0; while(fromEndIt < fromLength){ int replaceIt = 0; while(replaceIt < replaceLength && (fromEndIt+replaceIt) < fromLength && from[fromEndIt + replaceIt] == replace[replaceIt]){ ++replaceIt; } if(replaceIt == replaceLength){ //Update from buffer iterator positions toLength += (fromEndIt + replacementLength); from += (fromEndIt + replaceLength); fromEndIt = 0; continue; } ++fromEndIt; } toLength += fromEndIt; return toLength; } //Baller replaceString by Leif Messinger //Needs null terminated from, replace, and replacement strings as well as a large block of memory to store the result. void replaceString(char* to, const char* from, const char* replace, const char* replacement){ size_t fromLength = strlen(from); size_t replaceLength = strlen(replace); size_t replacementLength = strlen(replacement); size_t fromEndIt = 0; while(fromEndIt < fromLength){ int replaceIt = 0; while(replaceIt < replaceLength && (fromEndIt+replaceIt) < fromLength && from[fromEndIt + replaceIt] == replace[replaceIt]){ ++replaceIt; } if(replaceIt == replaceLength){ //Copy the string before the matched bit memcpyToAndShiftPointers(to, from, fromEndIt); //Copy the replacement too memcpyToAndShiftPointer(to, replacement, replacementLength); //Update from buffer iterator positions from += replaceLength; fromEndIt = 0; continue; //I don't want this thing to get incremented again } ++fromEndIt; } //Copy the rest of the unmatched string memcpyToAndShiftPointer(to, from, fromEndIt); to[0] = '\0'; //Should work } //===============replaceString.h=============== #ifndef REPLACE_STRING_H #define REPLACE_STRING_H #include <string.h> #define memcpyToAndShiftPointer(to,from,n); memcpy((to),(from),(n)); (to) += (n); #define memcpyToAndShiftPointers(to,from,n); memcpy((to),(from),(n)); (to) += (n); (from) += n; //Normally I'd make a replaceStringMalloc to return a malloced string or a replaceStringMut to change the original string, but I'm not satisfied with those function names so it's best just to do to = (char*)malloc(replaceStringLength(from, replace, replacement)); replaceString(to, from, replace, replacement); //If this was c++, I'd have no problem just overloading replaceString //Returns the length of the resulting string (minus the null char) size_t replaceStringLength(const char* from, const char* replace, const char* replacement); //Baller replaceString by Leif Messinger //Needs null terminated from, replace, and replacement strings as well as a large block of memory to store the result. void replaceString(char* to, const char* from, const char* replace, const char* replacement); #endif //===============replaceStringMain.c=============== #include <stdio.h> #include <stdlib.h> #include "replaceString.h" #define BUFFER_SIZE (1<<21) //About a mebibyte //There could be matches between buffers, so make sure the buffer size you set it to is good enough for your application. Basically as big as your input. //Replaces strings from sdtin, then outputs it to stdout //./a.out [[replace], [replacement]]... int main(int argc, char** argv){ char* buffer1 = (char*) malloc(BUFFER_SIZE); char* buffer2 = (char*) malloc(BUFFER_SIZE); if(buffer1 == NULL || buffer2 == NULL){ perror("You need a couple MBs of ram my boy"); return 1; } while(!feof(stdin)){ fread(buffer1, BUFFER_SIZE, 1, stdin); char* activeBuffer = buffer1; char* inactiveBuffer = buffer2; char* tmp; for(size_t i = 1; (i + 1) < argc; i += 2){ //puts(activeBuffer); replaceString(inactiveBuffer, activeBuffer, argv[i], argv[i+1]); //Swap buffers tmp = activeBuffer; activeBuffer = inactiveBuffer; inactiveBuffer = tmp; } fputs(activeBuffer, stdout); } free(buffer1); free(buffer2); return 0; }

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