All Questions
102 questions
94
votes
4
answers
111k
views
Is it possible to print out only a certain section of a C-string, without making a separate substring?
Say I have the following:
char *string = "Hello, how are you?";
Is it possible to print out only the last 5 bytes of this string? What about the first 5 bytes only? Is there some variation ...
- 4,365
26
votes
3
answers
18k
views
Is sprintf(buffer, "%s […]", buffer, […]) safe?
I saw use of this pattern to concatenate onto a string in some code I was working on:
sprintf(buffer, "%s <input type='file' name='%s' />\r\n", buffer, id);
sprintf(buffer, "%s</td>", ...
- 9,674
22
votes
9
answers
5k
views
'\0' and printf() in C
In an introductory course of C, I have learned that while storing the strings are stored with null character \0 at the end of it. But what if I wanted to print a string, say printf("hello") although I'...
- 421
11
votes
6
answers
2k
views
Unexpected printf output [duplicate]
I just discovered very weird behavior from the C compiler. It's very simple code. I tried it in many online C compilers, but the result is always the same, which is driving me insane.
#include <...
- 289
7
votes
5
answers
911
views
What will be the output, if we print a string that contains "%s" in it?
I'd like to know what the result would be if we print a string that contains "%s" in its content?
I tried printing it as "hi%s".
char *ptr="hi%s";
printf(ptr);
I expected the output to be as "hi".
...
- 111
5
votes
3
answers
3k
views
Format string with multiple percent signs
I know %% is used to escape actual % signs in a string, so %%%ds will end up with %10s in the following format string, but I don't know why I need %%5s in this string?
After all, there are only two ...
- 4,395
5
votes
1
answer
67
views
Portablilty of using percison when printf-ing non 0 terminated strings
As multiple questions on here also point out, you can printf a nonterminated string by formatting with a precision as maximum length to print. Something like
printf("%.*s\n", length, str);
...
- 1,924
4
votes
3
answers
726
views
Does each call to printf() create a new internal buffer, or do all subsequent calls use the same buffer as the first?
When I was working on a small program using printf(), I noticed that each \t character used in following printf() calls continued from the end of the string in the previous printf() call.
The ...
user7183038
3
votes
10
answers
1k
views
using 0 instead of '\0' in C program
why my program did not go in infinite loop. I have not used '\0' for testing string end in while loop, instead of that I have use 0. Does '\0' and 0 same in C?
If yes, then if 0 is in the middle of a ...
- 303
3
votes
1
answer
1k
views
How to concat strings in for loop with snprintf or similar function (C)?
I have the following code, which is my attempt to make a single string containing the stored HTTP header fields:
typedef struct _header {
char* name;
char* value;
} header;
const header ...
- 1,258
2
votes
3
answers
190
views
Why is the strlen here equal to 25?
Just so I can confirm if what I think is going on is really going on. The following code prints out 25 when I give it the (26 letter) alphabet as an input, is it because fgets always automatically ...
2
votes
2
answers
8k
views
Is printf unsafe to use in C
I am new to C so I started playing around with some code. I have a bug in my code as I believe using printf(pass) is not safe to use because it can overwrite the value and hence not safe for the user. ...
user14287969
2
votes
2
answers
1k
views
Why is the printf specifiers, "%s", printing multiple variables at once?
I declared four string variables and initialized in four different ways. I then used the printf function four times, as the name implies, to print to the console the four string variables.
I already ...
- 153
2
votes
1
answer
430
views
Playing with pointers, dazed and confused by char * strings
So i was playing with pointers to understand different use cases, I'm not so experienced at this and unable to wrap my head around some ideas. I'll mark the lines where i have a problem.
Please help ...
- 60
2
votes
2
answers
5k
views
Why is printf causing a segmentation fault? [closed]
I have this code:
char* env;
if (getenv("MP") == NULL)
{
env = "/usr";
}
else
{
env = getenv("MP");
}
printf("($MP is %s)\n", env);
printf("The program seg faults without printing me :(");
...
- 542