Get a space in a multidimensional array - c

Question

I am trying to get a name in an array " char name[100][100]". I tried doing many thing like these, but none work.Can you help me?
The code: Its a simple student's grade system i think, but only prints "" when trying to save a name.
#include <stdio.h>
#include <string.h>
void insert();
char name[100][100];float f[20];int z;
int main()
{
int x=0;
do{
printf("<1> Insert student\n");
printf("=> ");
scanf("%d",&x);
printf("\n*************************************************************\n");
switch(x){
case 1:
insert();
break;
default: printf("NO");
break;
}
}while(insert >=0 );
return 0;
}
void insert()
{
int x;
int y=0;
float n1,n2,p;
printf("How many students?: ");
scanf("%d",&y);
for(x=0;x<y;x++){
printf("Insert name: ");
fgets(name[x], 100, stdin);
int len = strlen(name[x]);
if (name[x][len-1] == '\n') {
name[x][len-1] = '\0';
}
printf("name[%d] = \"%s\"\n", x, name[x]);
printf("Insert first grade: ");
scanf("%f",&n1);
printf("Insert second grade: ");
scanf("%f",&n2);
printf("Insert final grade: ");
scanf("%f",&p);
f[x] = (n1 * 0.3)+(n2 * 0.3)+(p * 0.4);
z++;
}
for(x=0;x<z;x++){
if(f[x] < 6){
printf("the final grade of %s is: %.2f \n",name[x], f[x]);}
else{printf("the final grade de %s es: %.2f \n",name[x], f[x]);}
}
}

Answer 1

You should bear in mind that fgets() returns the new-line as well, if there's enough space in the buffer. You might want to take it out:
#include <stdio.h>
#include <string.h>
int main()
{
char name[100][100];
int y = 5;
int x = 0;
for (x = 0; x < y; x++) {
printf("Insert name: ");
fgets(name[x], 100, stdin);
int len = strlen(name[x]);
if (name[x][len-1] == '\n') {
name[x][len-1] = '\0';
}
printf("name[%d] = \"%s\"\n", x, name[x]);
}
}

Answer 2

Why are you using that %[^\t\n] string format? You should just go with a %s string format if you want to read a string (or, better, a %100s to limit the number of characters read).
scanf("%100s",name[x]) works just fine, but will mess things up when you try to use spaces (i.e. the scanf() will read one word at a time).
To avoid that, you can use the second option, that is fgets(). But, in this case, you need to pay attention to the final \n character that is appended to the string. To prevent the newline character from ending your string, you can simply do the following:
name[x][strlen(name[x])-1] = 0;
The previous code simply replaces the \n character with a null byte, thus ending the string and "ignoring" the newline.
EDIT:
The thing you need to understand is that the standard input (i.e. the keyboard input usually) is handled as if it were a file (in fact, you can use functions like fgets(), as if you were reading a normal file). So, as it happens with normal files, each line ends with a special character, \n. Every time you enter an input, and you press "Enter", a newline character is appended to your input.
There's a couple of things you need to know to understand what it is that you're doing wrong:
Some functions (like fgets()) read a line until a newline character is found. The newline character is also read, and returned in the string that was just read.
Other functions (like scanf()) also read lines until some special characters (such as or \n) are found. But, in this case, the final character is not read.
And, last: every time you open a file, the process keeps count of the number of characters you have read from the beginning of the file (or, to put it in an easier (and more correct) way, it "stores" a "pointer" to the next character that should be read).
With this being said, let's have a look at what happens with your program: first, the number of students is read (using scanf()), and, then, a name is read (using fgets()).
So, your input "file", looks like:
4\n
^
John Smith\n
...
The ^ is a pointer to the next character that should be read (and isn't, obviously, part of the input).
After the scanf() (which, as I mentioned, won't read the \n), the situation will be the following:
4\n
^
John Smith\n
...
Now, when you read the next line using fgets(), the "pointer" is already pointing to a newline character, and will therefore assume (correctly!) that the line has ended. The string you are reading is therefore "\n", instead of "John Smith\n".
The easiest way to fix this problem is to read, after every scanf(), single characters from standard input until a newline character is encountered.
scanf ( ... );
while (getc(stdin)!='\n');
Usually reading a single character should be enough, but in some cases (e.g. 4 \n) a single getc() isn't effective.
Basically, whenever a character is read from the file, the "pointer" is updated.
I really hope this cleared things up a bit. It isn't that easy to understand these details at first but, as you get more experience, things will definitely become clearer!