#include <stdio.h>
int main(){
int l,m,q,j;
char option;
scanf("%d",&q);
printf("%d\n",q);
for(j=0;j<q;j++){
scanf("%c %d %d",&option,&l,&m);
printf("%c %d %d",option,l,m);
}
return 0;
}
Output:
3(Input)
3
C 1 4(Input)
0 -374066224C 1 4
What is wrong with the above code? It is not giving the expected output.
There is still a newline character in the input stream from the initial scanf() (and subsequent scanf()s): this will be assigned to option and the subsequent int assignments will fail as C is not an int, meaning l and m are uninitialised int variables.
To skip it add a leading space character to the format specifier of the scanf() within the for loop:
scanf(" %c %d %d",&option,&l,&m);
/* ^ */
The return value of scanf() is the number of successful assignments made: check it to ensure 3 assignments are made.
if (3 == scanf(" %c %d %d",&option,&l,&m))
{
/* Valid input. */
}
3 and hit return. The return inserts a new line character into the input stream. The new line character is not consumed by the scanf(), leaving it in the input stream.
Every time you prompt the user for an input, they will write it and then press enter. Enter leaves a line feed character in the input buffer. You must discard it before asking for a character input, or it will end up in your character variable.
The easy but blunt solution is this:
scanf("%d",&q); getchar();
printf("%d\n",q);
for(j=0;j<q;j++){
scanf("%c %d %d",&option,&l,&m); getchar();
printf("%c %d %d",option,l,m);
}
(I'm pretty sure there is a C FAQ for this somewhere but I can't find the link.)