You can do it like this:
double a;
scanf("%lf", &a);
printf("%.1lf", a);
If you want to round off a double to only N decimal place, you can use %.Nlf instead of %.1lf .
Answer from gsm on Stack Overflow Top answer 1 of 2
1
You can do it like this:
double a;
scanf("%lf", &a);
printf("%.1lf", a);
If you want to round off a double to only N decimal place, you can use %.Nlf instead of %.1lf .
2 of 2
0
There are a few few ways you can go about this. If you want to go the rounding direction you can use round() to achieve it.
double a;
scanf("%lf", &a);
// Round to one decimal place
double rounded_value = round(a * 10) / 10;
printf("%.1f\n", rounded_value);
You can change out the round() for a few things but using printf("%.1f\n", ) is the key.
Reddit
reddit.com › r/cpp_questions › how do i round a double to one decimal?
r/cpp_questions on Reddit: How do I round a double to one decimal?
October 9, 2023 -
I want to round a double to one decimal point. I tried using round() but it doesn’t work the way I need it. I want to round it so 45.892 is 45.9. How would I do this?
Top answer 1 of 5
20
For surprisingly many cases, rounding a double/float in-place is probably not the right thing you actually want to do. To show it to a user / print a double / or converting it to string, use one of the following depending on how you usually handle string I/O: For printf / sprintf, use %.1f format specifier. For streams (std::cout / std::ostringstream usually), use std::setprecision https://en.cppreference.com/w/cpp/io/manip/setprecision For std::format, use {.1f} format specifier. When the result value has to be up to x decimal digits, consider using integers instead of doubles for result values: int i = static_cast(d * 10 + 0.5); This might not be accurate because of floating point roundings and inaccuracies... When the result of rounding has to be a floating point number, do as another comment suggests: multiply by a number by 10, round it, then divide it by 10. However, note that doing so sometimes yield incorrect values because of the nature of IEEE floating point numbers.
2 of 5
18
Multiply by 10, round, divide by 10. It's worth noting that some decimal values can't be represented by a double.
Quora
quora.com › How-do-I-round-a-float-to-1-decimal-place-after-a-division-in-C
How to round a float to 1 decimal place after a division in C++ - Quora
Answer (1 of 5): I usually multiply by 10, cast to an int, then cast back to a float, then divide by ten. Casting to int cuts off everything below 1, but since we've just multiplied by 10, we're cutting off eveything below 1.0 It looks like this: float v = 12.34; v = ((float )((int)(v * 10)))...
Quora
quora.com › How-do-you-handle-the-rounding-of-decimal-places-in-C-C-float-rounding-development
How to handle the rounding of decimal places in C (C, float, rounding, development) - Quora
If this number is 5 or greater, round up. If it is 4 or lower, round down. The decimal point in the middle doesn't change anything. For example, if you needed to round the example number from earlier (12.9889) to the nearest whole number, you'd start by looking at the ones place: 1.9889.
OpenGenus
iq.opengenus.org › rounding-and-truncating-numbers-in-c
Rounding and Truncating numbers using math.h in C
November 10, 2019 - It takes a floating value as argument and rounds the decimal part of it. It returns value in floating type format. If we pass float number as an argument, the syntax is: ... #include <stdio.h> #include <math.h> int main() { printf("roundf(+2.311) gives = %+.1f\n", roundf(2.311)); //here %+.1f is used to print only one place after decimal }
Arduino Forum
forum.arduino.cc › projects › programming
Round with one decimal point - Programming - Arduino Forum
April 28, 2022 - I have problem. SHT temperature is 24.37 and rouding temp = 24.37 and it should have been 24.3. Why does it still show two decimal places? I have code: float temp = (sht.getTemperature() * 10) / 10; float temp = (raw * 10) / 10;
Reddit
reddit.com › r/c_programming › decimal places
r/C_Programming on Reddit: Decimal places
September 15, 2018 -
Can I create a variable and set it to a specific decimal place? For example "float z to 5 dp" where z would be recorded to 5 dp for the rest of the program
Top answer 1 of 5
8
Can you use an integer and add in a decimal point when you display it? A lot of times when software is doing something with money amounts people will just store, say, $15.00 dollars as 1500. You can end up with inaccuracies trying to store these as a float and rounding because floating point numbers are stored as binary and not base 10.
2 of 5
3
Not like you're saying, but in a sense. If the decimal point doesn't move it's not floating point - it's fixed point. To use a simple example, instead of recording dollars to two decimal places, you would record cents, in an integer type. If you want to display dollars, it's up to you to remember that it's in cents and to convert appropriately for display. One of my applications has functions that take frequencies in Hertz, but they need at least 1/10 Hz resolution, so my frequency variables are declared like uint32_t freq_hz_q8. The 'hz' part is because I always try to include units for that sort of thing, and 'q8' signifies that the low 8 bits are the fractional portion. Thus 1 is actually 1/256 Hz. That doesn't convert cleanly to a fixed number of decimal places in base 10, but it does let you represent exact values (unlike floating point) and you know exactly what your range and resolution are.
Top answer 1 of 14
2
[image] dcrand:
temperature = (voltage - 0.5) * 100 * 9.0 / 5.0 + 32;
C++11 comes along with some neat math functions, one of them being round.
To use it as you wished, just add following after you set the temperature:
temperature = round(temperature*10)/10;
It will shift the original valu…
2 of 14
0
Thanks that works my coding skills are little to none.
W3Schools
w3schools.com › c › c_data_types_dec.php
C Data Types Decimal Precision
If you want to remove the extra zeros (set decimal precision), you can use a dot (.) followed by a number that specifies how many digits that should be shown after the decimal point: float myFloatNum = 3.5; printf("%f\n", myFloatNum); // Default will show 6 digits after the decimal point printf("%.1f\n", myFloatNum); // Only show 1 digit printf("%.2f\n", myFloatNum); // Only show 2 digits printf("%.4f", myFloatNum); // Only show 4 digits Try it Yourself »
TutorialsPoint
tutorialspoint.com › cplusplus-program-to-round-a-number-to-n-decimal-places
C++ Program to Round a Number to n Decimal Places
In our example, there is a negative number - 45.69 here after rounding it off, it is turning it into -46 which is smaller than this. So round() method is not like floor() or ceil(). Representing floating point numbers up to n decimal places has few approaches when we are writing code in C++. ...
Scaler
scaler.com › home › topics › c round() function
C round() Function - Scaler Topics
March 27, 2024 - The syntax of the round function is very simple, it just accepts one argument which can be float, int, or double, and it returns the integer by rounding it off to the accurate value. Its generic syntax is as follows · Here the num variable can be of float, or double type and the roundedValue will be an integer returned by the round() function and the roundedValue will not contain any decimal part.
Unreal Engine
forums.unrealengine.com › development › programming & scripting › blueprint
Need to round float to one decimal point. Why is it so difficult? - Blueprint - Epic Developer Community Forums
I just need to round a float to one decimal point but nothing is working. The most common response is to multiply my number by 10, floor it into an integer, then divide it by 10 again to turn it back into a float. It doesn’t work. I keep ending up with results like 2.100002 or 8.699998 Numbers that end in .0 or .5 work properly but everything else is off by .000002 and I can’t figure out why.
Published April 7, 2023
22web
randy.22web.org › classes › cop2000.c › rounding.html
How to Round a Number in a C Program
March 1, 2005 - This site requires Javascript to work, please enable Javascript in your browser or use a browser with Javascript support
HPE
support.hpe.com › hpesc › public › docDisplay
C: How to round off to the nearest two decimal places
We cannot provide a description for this page right now
Top answer 1 of 16
489
If you just want to round the number for output purposes, then the "%.2f" format string is indeed the correct answer. However, if you actually want to round the floating point value for further computation, something like the following works:
#include <math.h>
float val = 37.777779;
float rounded_down = floorf(val * 100) / 100; /* Result: 37.77 */
float nearest = roundf(val * 100) / 100; /* Result: 37.78 */
float rounded_up = ceilf(val * 100) / 100; /* Result: 37.78 */
Notice that there are three different rounding rules you might want to choose: round down (ie, truncate after two decimal places), rounded to nearest, and round up. Usually, you want round to nearest.
As several others have pointed out, due to the quirks of floating point representation, these rounded values may not be exactly the "obvious" decimal values, but they will be very very close.
For much (much!) more information on rounding, and especially on tie-breaking rules for rounding to nearest, see the Wikipedia article on Rounding.
2 of 16
130
Using %.2f in printf. It only print 2 decimal points.
Example:
printf("%.2f", 37.777779);
Output:
37.77
Reddit
reddit.com › r/c_programming › rounding in c
r/C_Programming on Reddit: Rounding in C
May 8, 2024 -
I have a question when it comes to rounding in C. Does it round up or down at .5? If it does round up, then does that mean that the smallest value of k in the code below can only be 1?
int main()
{
int k = 13;
int i;
for (i = 0; i < 8; i++) {
printf("%d", (k%2));
k >>= 1;
}
printf("%n");
}
Facebook
facebook.com › groups › cs50 › posts › 283176061829446
Rounding a floating point number to the 2nd decimal ...
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Simplilearn
simplilearn.com › home › resources › software development › setprecision() function in c++ with examples
setprecision() Function in C++ with Examples
July 31, 2025 - Master C++ setprecision() easily with concise explanations and examples. Control floating-point precision for optimal output formatting. Boost your skills!
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GeeksforGeeks
geeksforgeeks.org › c language › g-fact-41-setting-decimal-precision-in-c
Setting decimal precision in C - GeeksforGeeks
January 10, 2025 - // C program to set precision in floating point numbers // using format specifier #include<stdio.h> int main() { float num = 5.48958123; // 4 digits after the decimal point printf("%0.4f", num); return 0; }
Qt Forum
forum.qt.io › home › qt development › general and desktop › rounding a real number to nth place of decimal
Rounding a real number to nth place of decimal | Qt Forum
March 2, 2022 - I want to round the real value to specific decimal places because I don't want to store other digits in my database. Use cases can be any real number like round(54.3467,2) = 54.35 , round(5.842) = 6 , round(8.54123,4)=8.5412 ..so on