Member Avatar for gladiator1919

plz i want your help.

if i wrote a string and the user wanted to change a word in it.

sample run:

the sentence is;

my name is gladiator

what word do you change?

gladiator

to?
gladiator1919

the new sentence is :

my name is gladiator1919

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  • Latest Post Latest Post by Dave Sinkula

Dani AI

Generated

Short answer: in C there is no std::string::find/replace like mentioned for C++; do it manually with strstr (or tokenization) and rebuild the result. Also note 's idea of splitting into words is valid, but avoid the unsafe functions shown in that sketch — and is right: never use gets or unchecked scanf for line input. Use fgets, trim the newline, then search and construct a new string (or allocate one) safely.

The snippet below replaces all occurrences of a substring with another substring and returns a malloc'd result (caller must free it). It shows a safe input pattern using fgets; it performs substring replacement (not "whole-word only"). For whole-word or case-insensitive behavior, add boundary checks or normalize case before searching.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/* returns malloc'd string with all occurrences of oldw replaced by neww */
char *replace_all(const char *s, const char *oldw, const char *neww) {
    if (!s) return NULL;
    if (!oldw || !*oldw) { char *r = malloc(strlen(s)+1); if (r) strcpy(r,s); return r; }
    size_t sl = strlen(s), ol = strlen(oldw), nl = strlen(neww);
    const char *p = s; size_t count = 0;
    while ((p = strstr(p, oldw))) { count++; p += ol; }
    size_t newlen = (nl >= ol) ? sl + count*(nl-ol) : sl - count*(ol-nl);
    char *res = malloc(newlen + 1); if (!res) return NULL;
    char *dst = res; const char *src = s;
    while ((p = strstr(src, oldw))) {
        size_t prefix = p - src;
        memcpy(dst, src, prefix); dst += prefix;
        memcpy(dst, neww, nl); dst += nl;
        src = p + ol;
    }
    strcpy(dst, src);
    return res;
}

/* Example usage: read a sentence and two words with fgets, then call replace_all */

Notes and tips: always check return values, free the returned string, and adjust buffer sizes for expected input. To restrict to whole-word replacements, verify characters before/after each match are non-alphanumeric (or use isalnum/ispunct checks). For case-insensitive replace, search in lowercase copies and map indices back to the original.

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Member Avatar for gladiator1919

what is the code to do this?

Member Avatar for SpS

You can use find and replace function of string class.

Member Avatar for gladiator1919

how can i call find and replace function from the string class

Member Avatar for Member #46692

how can i call find and replace function from the string class

by utilising google?

Member Avatar for ivanCeras

C.... code.. its up for you to translate to C++
and correct other situations.. like no string is entered....

#include<stdio.h>
#include<string.h>

#define MAX_LEN_WORD 80
#define MAX_NO_WORDS 100

main(){
   char buffer[MAX_LEN_WORD]="";
   char word[MAX_NO_WORDS][MAX_LEN_WORD];
   int word_counter = 0;

    printf("Enter string");
    gets(string);
/*separating the words */
    len = strlen(string);
    for(x=0;x<len;x++){
         if(string[x]==' '){
          strcpy(word[word_counter],buffer);
          word_counter++;
         buffer = "";
     }
     buffer[x] = string[x];
  }

 printf("What word would you like to change");
  scanf("%s",&change);

/*looking fo that word..  */
  for(x=0;x<word_counter;x++){
     if(strcmp(change,word[x])==0){
           strcpy(word,change);
       }
  }

/*concatening the words back */
for(x=0;x<word_counter;x++){
    strcat(final_sentence,word[x]);
}
/*printing the sentence back..*/

puts(final_string); 
getch();

}

those codes of mine are not tested by the way... just try reading the flow of it... dont just copy the code directly to your program... anyways.. i assume you are not new to programming....

Member Avatar for Dave Sinkula 
main(){

Wake up and smell the current millenium, or even the '90s.

gets(string);

I know of no forums that will treat you any better than a first-day newb for posting code contiaining the most well-known do-not-use-ever function in C.

scanf("%s",&change);

http://www.daniweb.com/tutorials/tutorial45806.html

getch();

The nonportable code tends to get panned if there is a reasonable and portable replacement.

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