how to remove a character from a string with loop? - c

Question

Im trying to make the program remove a character from a string that the user is putting in but i get an error inside the loop. (side question: is adding a character inside the string the "same" code with some small changes?)
PS New to programming...

Answer 1

Is this what you are trying to achieve?
Changes:
getchar() and fgets() to scanf()
added strlen() to get length of string
added lenght of input string to printf
added zero init of strings
Note: After each input with scanf() you have to press enter.
int main()
{
char str[100] = { 0 };
char ch[5] = { 0 };
int k, j;
printf("Write text:\n");
scanf("%s", str);
printf("Input was: %s\nLength: %d\n", str, strlen(str));
printf("Write a character that should be removed\n");
scanf("%s", ch);
for (k = 0, j = 0; k < strlen(str); k++)
{
if (str[k] != ch[0]) {
str[j] = str[k];
j++;
}
}
str[j] = '\0';
printf("String after removing a character: %s", str);
}

Answer 2

Problems with your code:
str[k] != ch would be a valid test if ch were indeed a character and not an array of characters of length 5. This is going to compare the character value of str[k] with the address &ch[0].
k < str would be a valid comparison if k was a char * pointer that was initialized at &str[0], not an int loop index starting at 0.
Corrected code:
int main(void)
{
char str[100];
char ch[5];
int k, j;
printf("Write text:\n");
//getchar();
fgets(str, 100, stdin);
printf("Input was: %s\n", str);
printf("Write a character that should be removed\n");
//getchar();
fgets(ch, 5, stdin);
for (k = 0, j = 0; k < strlen(str); k++)
{
if (str[k] != ch[0])
{
str[j] = str[k];
j++;
}
}
str[j] = '\0';
printf("String after removing a character = %s", str);
return 0;
}

Answer 3

Here you have two implementations. Both remove all occurrences of the char ch from the string str
First algorithm is much faster. The second slower but easy to understand
#include <stdio.h>
#include <string.h>
char *removechar(char *str, int ch)
{
char *cptr = str, *readptr = str;
while(*readptr)
{
if(*readptr == ch)
{
readptr++;
}
else
{
*cptr++ = *readptr++;
}
}
*cptr = 0;
return str;
}
char *removechar(char *str, int ch)
{
char *cpos = str;
while((cpos = strchr(cpos, ch)))
{
strcpy(cpos, cpos + 1);
}
return str;
}
int main()
{
char s[] = "Hello World";
printf("%s\n", removechar(s, 'd'));
printf("%s\n", removechar(s, 'l'));
return 0;
}

Answer 4

Is this what you want to achieve?
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
int main(){
char str[100],c;
printf("Write text:\n");
fgets(str,100,stdin);
printf("Input was: %s\n", str);
printf("Write a character that should be removed\n");
c=getchar();
for(int k=0;k<strlen(str);k++){
if(str[k]==c){
for(int j=k;j<strlen(str);j++){
str[j]=str[j+1];
}
}
}
printf("String after removing a character = %s", str);
return 0;
}