How to delete all that match - c

Question

Right now this function is deleting the last name given by the user from a list, but I need it to delete all the names that match the name given by the user, not just the first occurrence of the user input, and need to free up allocated memory of the names that got deleted. How can I do this?
int deleteR(char**Fname,char **Lname,float *score,int count)
{
int i=0,j=0;
char *Lastname;
printf("\n Enter the Last Name of the Student you would like to delete from the records. ");
Lastname = (char *)malloc(15 * sizeof(char));
printf("\nLast Name: ");
scanf("%s",Lastname);
int counter = count;
for(i=0;i<count-1;i++)
{
if(strcmp(Lname[i],Lastname)==0)
{
for(j=i;j<count;j++)
{
Lname[j]=Lname[j+1];
Fname[j]=Fname[j+1];
score[j]=score[j+1];
}
counter--;
}
}
count=counter;
return count;
}

Answer 1

In case your loop on j remove entries because you do not change count later in a loop on i you will access values already checked and may freed because removed
You also have a memory leak because you allocate memory for Lastname but you never free it, and in fact there is no reason to not have Lastname as an array in the stack. Also your scanf can write out of Lastname without limit in size.
You do not need to have two embedded loops as you do, only one is enough to move entries managing an index to write and an other to read :
int deleteR(char**Fname, char **Lname, float *score, int count)
{
char lastname[16];
printf("\nEnter the Last Name of the Student you would like to delete from the records: ");
if (scanf("%15s", lastname) == 1) {
int i;
/* that first loop to search if the lastname is present */
for (i = 0; i < count; ++i) {
if (!strcmp(Lname[i], lastname)) {
/* at least present one time, update lists */
int futureCount = count - 1;
int j;
/* it seems you want to free removed resources */
free(Lname[i]);
free(Fname[i]);
/* that loop to move useful elements */
for (j = i + 1; j < count; ++j) {
if (strcmp(Lname[j], lastname)) {
/* still usefull */
Lname[i] = Lname[j];
Fname[i] = Fname[j];
score[i] = score[j];
i += 1;
}
else {
/* useless */
/* it seems you want to free removed resources */
free(Lname[j]);
free(Fname[j]);
futureCount -= 1;
}
}
return futureCount;
}
}
}
else
puts("EOF");
return count;
}
Using that main function to check :
int main()
{
char * fname[5];
char * lname[5];
float score[5];
int count, i;
fname[0] = strdup("Wolfgang Amadeus");
lname[0] = strdup("Mozart");
score[0] = 0;
fname[1] = strdup("Johann Sebastian");
lname[1] = strdup("Bach");
score[1] = 1;
fname[2] = strdup("Leopold");
lname[2] = strdup("Mozart");
score[2] = 2;
fname[3] = strdup("Johann Christian");
lname[3] = strdup("Bach");
score[3] = 3;
fname[4] = strdup("Ludwig van");
lname[4] = strdup("Beethoven");
score[4] = 4;
count = deleteR(fname, lname, score, 5);
printf("new lists:\n");
for (i = 0; i != count; ++i)
printf("%s %s : %g\n", fname[i], lname[i], score[i]);
return 0;
}
Compilation and executions :
pi#raspberrypi:/tmp $ gcc -Wall d.c
pi#raspberrypi:/tmp $ ./a.out
Enter the Last Name of the Student you would like to delete from the records: Chopin
new lists:
Wolfgang Amadeus Mozart : 0
Johann Sebastian Bach : 1
Leopold Mozart : 2
Johann Christian Bach : 3
Ludwig van Beethoven : 4
pi#raspberrypi:/tmp $ ./a.out
Enter the Last Name of the Student you would like to delete from the records: Mozart
new lists:
Johann Sebastian Bach : 1
Johann Christian Bach : 3
Ludwig van Beethoven : 4
pi#raspberrypi:/tmp $