Move decimal point to where you want to round up, do round up and move it back.
ceil(value * 1000.0) / 1000.0
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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.
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Using %.2f in printf. It only print 2 decimal points.
Example:
printf("%.2f", 37.777779);
Output:
37.77
How do I round up decimal places? - C++ Forum
I'm taking a math oriented programming class and this assignment involves some payments. If a calculation for a payment comes out to something like this: 100.251, I want to round that value up to 100.26. Using fixed and setprecision(2) uses normal rounding rules. More on cplusplus.com
Rounding in C
Have you considered simply trying the code out? More on reddit.com
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0
May 8, 2024Decimal places
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. More on reddit.com
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September 15, 2018Rounding offto 2 decimal points - C++ Forum
If all you want to do is print ... place, use the stream manipulators: However, if you want to actually modify the numeric value, you'll need to multiply, round, and divide. The caveat is that this might not do exactly what you think. The reason is that floating point numbers are not exact. And the reason for that is twofold: (1) numbers in the computer are represented in binary but we view them in decimal, which is ... More on cplusplus.com
Videos
03:33
C# 35: Round a number to 3 decimal places using Math.Round - YouTube
04:17
C 11: Show a number in 3 decimal places without rounding - using ...
08:10
Round A Double To A Specific Number Of Decimal Places | C Programming ...
04:13
C Programming Tutorial - 36 - Rounding Numbers - YouTube
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
The C standard math library has ... 3 decimal places - then multiply the number by 1000, use the ceil, floor or round function depending on which way you want to round - then divide by 1000....
OpenGenus
iq.opengenus.org › rounding-and-truncating-numbers-in-c
Rounding and Truncating numbers using math.h in C
November 10, 2019 - Truncated value of 3.04 is 3 Truncated value of 3.98 is 3 Truncated value of -3.31 is -3 Truncated value of -8.9 is -8 · round() is used to round a floating number to its nearest integer value whereas trunc() is used to remove the decimal values from a number.
Cplusplus
cplusplus.com › forum › beginner › 170942
How do I round up decimal places? - C++ Forum
closed account (E0p9LyTq) You want to round up to a more significant decimal place, in your stated case hundreths. Simply multiply by 100, use ceil() to round up and then divide by 100. Last edited on · closed account (E0p9LyTq) @supernoob, setprecision() only effects how the output is done.
Medium
medium.com › @ryan_forrester_ › how-to-round-in-c-complete-guide-e02c9e671050
How to Round in C++: Complete Guide | by ryan | Medium
October 2, 2024 - #include <iostream> #include <cmath> ... "Floor: " << std::floor(x) << std::endl; // Output: 3 return 0; } `std::ceil` always rounds up, while `std::floor` always rounds down. To round to a specific number of decimal places, you can use a combination of multiplication, rounding, ...
Oxford University
mathcenter.oxford.emory.edu › site › cs170 › printf
The printf Method
we now see that the format specifier "%.2f" tells the printf method to print a floating point value (the double, x, in this case) with 2 decimal places. Similarly, had we used "%.3f", x would have been printed rounded to 3 decimal places.
Sciencing
sciencing.com › round-numbers-three-decimal-places-8447024
How To Round Numbers To Three Decimal Places - Sciencing
July 26, 2023 - After you round the third digit, remove all the numbers following the third number to express the rounded number in its reduced form with only three digits following the decimal. This same process can be applied to any number of decimal places.
Quora
quora.com › How-do-I-round-off-a-float-to-2-decimal-points-in-C-like-3-01943-to-3-02
How to round off a float to 2 decimal points in C, like 3.01943 to 3.02 - Quora
Answer (1 of 7): If you have to round input floating point number then for that the format is “%wf” where w = Integer number for total width of data.(including the digit before and after decimal and decimal itself) Ex- scanf(“”,&x) For x = 3.01943 Result = 7.8 If you have to round ...
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.
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");
}
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
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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.
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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.
HPE
support.hpe.com › hpesc › public › docDisplay
C: How to round off to the nearest two decimal places
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Mathematics LibreTexts
math.libretexts.org › campus bookshelves › college of the desert › math 011: math concepts for elementary school teachers – number systems › 10: estimation and rounding
10.3: Rounding Decimals - Mathematics LibreTexts
November 11, 2023 - Note that the only real change to the method we saw in the previous section is that we need to consider what happens to the right of the round-off digit based on where it is in relation to the decimal point. Round 633.14216 to the nearest hundred. The digit immediately to the right is 3, and \(3 < 5\) so we leave the round-off digit unchanged.
Cplusplus
cplusplus.com › forum › beginner › 222475
Rounding offto 2 decimal points - C++ Forum
If all you want to do is print ... place, use the stream manipulators: However, if you want to actually modify the numeric value, you'll need to multiply, round, and divide. The caveat is that this might not do exactly what you think. The reason is that floating point numbers are not exact. And the reason for that is twofold: (1) numbers in the computer are represented in binary but we view them in decimal, which is ...
CalculatorSoup
calculatorsoup.com › calculators › math › roundingnumbers.php
Rounding Numbers Calculator
Increase the hundreds digit by one, so 2 becomes 3. Every digit after becomes a zero. ... Is that digit greater than or equal to five? No, so round down. The tens digit stays the same at 2. Every digit after becomes a zero.
TutorialsPoint
tutorialspoint.com › cplusplus-program-to-round-a-number-to-n-decimal-places
C++ Program to Round a Number to n Decimal Places
Number 45.278586 up to 3 decimal places: 45.279 Number 45.278586 up to 4 decimal places: 45.2786 Number 45.278586 up to 5 decimal places: 45.27859 · This is an ideal way to represent numbers up to n decimal places. Sometimes for n = 0, we can use another method to round them off.
W3Schools
w3schools.com › c › c_data_types_dec.php
C Data Types Decimal Precision
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 ...
Reddit
reddit.com › r/learnmath › what is 1.36363 to correct to 3 decimal places
r/learnmath on Reddit: What is 1.36363 to correct to 3 decimal places
November 24, 2020 -
So I'm a bit lost as i'm unsure what this would be rounded up. would it be 1.463 or 1.464 maybe? Dumb question I know but thanks!
Top answer 1 of 6
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You want to round up or down the very last number you are keeping, so it would be 1.364
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If last digit is 4 or less, don't round the number to the left of it up. If the last digit is 5 or more, round the number to the left up by one. I did some stalking... keep trying for the electrician thing! Its the will that takes you places. Never feel like you are making a stupid question, youd be surprised how many things people don't know or can't remember and won't even think about asking. Good luck!
Top answer 1 of 3
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The other person is correct. To round to the third decimal place, you look strictly at the the digit immediately to the right: $4$ in this case, and $4/10$ rounds to zero.
So you need to round $0.03446$ to $0.034$
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The other person is correct. Rounding is saying what number it is closer to. So which value is smaller: $|0.03446-0.034|$ or $|0.03446-0.035|$? The smaller value tells us which one we want to round to.