C, comparing arrays, find a character, - c

Question

So I am kinda new to coding, but what I want to do is write a string, write one character I wish not to be in the string if it occurs. I've tried using removedChar = getchar() instead of fgets(removedChar, 2, stdin); but then I can't do the != in the if statement.
I would really appreciate your help.
int main() {
char str[20], removedChar[2];
int i, n, j;
printf("ENTER A STRING:");
fgets(str, 20, stdin);
printf("ENTER WHAT CHAR YOU WISH TO REMOVE: ");
fgets(removedChar, 2, stdin);
n = strlen(str);
for (i = 0, j = 0; i < n; i++) {
if (strcmp(str, removedChar) == 0) {
str[j] = str[i];
j++;
}
if (str[i] == ' ') {
str[j] = str[i];
j++;
}
}
str[j] = '\0';
printf("string after removing character = %s", str);
system("pause");
return 0;
}

Answer 1

Firstly this line:
if (strcmp(str, removedChar) == 0)
is comparing if two strings are identical. Please see strcmp.
You need to instead compare character against characters, instead of equality of string against string.
Having said this, you can now just simply loop over the string, and use != to rule out matching characters, and update the string accordingly with a counter.
Additionally, it is always safe to check the return value of fgets, and also check that you havn't exceeded the buffer length.
This is the code that uses these ideas:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define STRSIZE 20
int
main(int argc, const char *argv[]) {
char str[STRSIZE];
int i, j, removedchar;
size_t slen;
printf("Enter a string: ");
if (fgets(str, STRSIZE, stdin) == NULL) {
printf("Error reading string\n");
return 1;
}
slen = strlen(str);
if (slen > 0) {
if (str[slen-1] == '\n') {
str[slen-1] = '\0';
} else {
printf("Error: Exceeded Buffer length of %d.\n", STRSIZE);
return 1;
}
}
if(!*str) {
printf("Error: No string entered.\n");
return 1;
}
printf("Enter what character you wish to remove: ");
removedchar = getchar();
if (removedchar == '\n') {
removedchar = ' ';
printf("No character was entered. Spaces will be removed if found\n");
}
j = 0;
for (i = 0; str[i] != '\0'; i++) {
if (str[i] != removedchar) {
str[j++] = str[i];
}
}
str[j] = '\0';
printf("Changed String = %s\n", str);
return 0;
}

Answer 2

You should use str[i] != removedChar[0] instead of using strcmp() which compares the full strings.
Also note that you should strip the newline character from the string read by fgets().
Here is a corrected version:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(void) {
char str[80], removedChar[80];
int i, n, j;
printf("ENTER A STRING: ");
if (!fgets(str, sizeof str, stdin))
return 1;
str[strcspn(str, "\n")] = '\0'; // strip the newline character if present
printf("ENTER WHAT CHAR YOU WISH TO REMOVE: ");
if (!fgets(removedChar, sizeof removedChar, stdin))
return 1;
for (i = 0, j = 0; str[i] != '\0'; i++) {
if (str[i] != removedChar[0]) {
str[j] = str[i];
j++;
}
}
str[j] = '\0';
printf("string after removing character = %s\n", str);
system("pause");
return 0;
}