Note however that this would be a reinterpret_cast, not a static cast, but from the way you describe your problem I think a reinterpret cast is what you want. Grappling and disarming - when and why (or why not)? Can the supreme court decision to abolish affirmative action be reversed at any time? Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, The future of collective knowledge sharing. storing float value to unsigned char array, Convert char pointer to unsigned char array. @WhozCraig . Convert from unsigned char array to float! searching for a way to convert a std::string to a unsigned char* atof takes as a parameter a char* (or char []) and returns a double: double atof (const char *str); So, assuming the aim is to convert a double to a string, atof isn't appropriate. In such condition type conversion (type promotion) takes place to avoid lose of data. Right, so static_cast is what I want to use to be safe then. I have experience in programming in general, but not VB.NET. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. convert jbytes to unsigned char before doing anything else, this will definetly restore the pixel values you are trying to manipulate, use a larger signed integer type, such as int while doing intermediate calculations, this to make sure that over- and underflows can be detected and dealt with (in particular, not casting to a signed type could force to compiler to promote every type to an unsigned type in which case you wouldn't be able to detect underflows later on), when assigning back to a jbyte, you'll want to clamp your value to the 0-255 range, convert to unsigned char and then convert again to signed char: I'm not certain the first conversion is strictly necessary, but you just can't be wrong if you do both. the signed char has value -100. How to describe a scene that a small creature chop a large creature's head off? The "add 256" strategy is for when the data has already been misinterpreted earlier. To convert the value (e.g. Can the supreme court decision to abolish affirmative action be reversed at any time? Grappling and disarming - when and why (or why not)? Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, The future of collective knowledge sharing. if you want to convert character array containing number to float here is the way. Usually this is done by implementing functions that unmarshall from std::vector to various types for example: but you need to be careful and use it only for POD types (maybe add std::enable_if to enforce it). You start off with -100, which is 10011100 in binary. Counting Rows where values can be stored in multiple columns. How to deploy AntDB Community Version on a virtual machine on VMware WorkstationP2, How to send live message and notification to all the Access Database frontend users, The next Access Europe meeting is on Wed 5 July - Interactive Gantt Chart Scheduler in Access. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Thank you. Is there no C library function that will take an int and convert it to its C++98 integer to floating point conversion had defined behavior in all cases the behavior is undefined if the value being converted is out of the destination range CWG 1423: How to standardize the color-coding of several 3D and contour plots? How Bloombergs engineers built a culture of knowledge sharing, Making computer science more humane at Carnegie Mellon (ep. well, this would go wrong on any architecture that does not use two's complement for signed characters, the simple cast would work regardless of the signed number implementation. Implicit Type Conversion Also known as 'automatic type conversion'. There are two types of Conversion: 1. Additionally in ones' complement the 0b11111111 bitvalue would not be -1, but -0, (yes this value exists in ones' complement,) and would be converted to a value of 0 with a static_cast, but a value of 255 with a reinterpret_cast. I have edited to add my program. Find centralized, trusted content and collaborate around the technologies you use most. Convert 4 bytes to 32 bit float with high precision in C? Join Bytes to post your question to a community of 472,485 software developers and data experts. and I have printed it on the screen using You pass in the float, how wide you want the whole number to be (if it will fit), the number of decimals of precision - and the buffer you want it to fill. I have a 32 bit unsigned value that I want to convert to ieee 754 floating point. But thanks :). But I dont want to create another variable to hold the float. Similarly in the other direction. Convert float to unsigned char in C | Convert Data Types Convert data types programming in one click ! Just copy it back to float: float value; std::copy ( readRequestArray.begin (), readRequestArray.end (), reinterpret_cast<const unsigned char*> ( &value ) ); Usually this is done by implementing functions that unmarshall from std::vector<byte> to various types for example: How one can establish that the Earth is round? Goran Hi! true signed data), or 0 is the lowest value, 127 is somewhere in the middle, and the next "higher" number is -128, with -1 being the "highest" value (that is, the most significant bit already got misinterpreted as a sign bit in a two's complement notation. Whether the result is a sentinel or saturated value or not depends on the compiler options and target architecture. To learn more, see our tips on writing great answers. I'm a bit confused by the pointer cast in your sample though. Thus, casting an integer value to a float type just yields a float that best represents the original integer value; but type-punning an integer value (of the same size as a float) to float means the storage representation of that integer value is treated as the storage representation of a float value, yielding the float value that has the same storage representation as the original integer value has. Do I owe my company "fair warning" about issues that won't be solved, before giving notice? This won't work. Index 3 2 1 0 Insert records of user Selected Object without knowing object first. union U u; And the second method doesn't invoke UB either. If I got it right, you are reading jbytes that are technically signed chars, but really pixel values ranging from 0 to 255, and you're wondering how you should handle them without corrupting the values in the process. floating point - Convert char to float in c - Stack Overflow For example: If for example value == 2.125, then my_truncate(value) == 2. This is known as a standard conversion. Is there and science or consensus or theory about whether a black or a white visor is better for cycling? Latex3 how to use content/value of predefined command in token list/string? can you please tell me the way back from the char array to the float number ? Can't see empty trailer when backing down boat launch. In TikZ, is there a (convenient) way to draw two arrow heads pointing inward with two vertical bars and whitespace between (see sketch)? The client sends Does the debt snowball outperform avalanche if you put the freed cash flow towards debt? Connect and share knowledge within a single location that is structured and easy to search. Instead of 1.0 floatVal gets a value of 1.0653532e+009. I am not 100% sure however if this would be guaranteed to work by the standards. Home Posts Topics Members FAQ home > topics > c / c++ > questions > convert from unsigned char array to float! So the ASCII value 97 will be converted to a character value, i.e. #. @scott: I mean what input numbers generated this specific output? so the 2.45 should look like this '@' 'FS' '' '' which is binary the ieee representation of 2.45 = 01000000 00011100 11001100 11001101? This is exactly what the float_bits() example function above does. How to convert a char array to a float array? Why is inductive coupling negligible at low frequencies? float to signed integer conversion does not match float to unsigned integer, Converting a float* or other pointer to unsigned char*, OSPF Advertise only loopback not transit VLAN. c - casting from unsigned int to float - Stack Overflow Does the Frequentist approach to forecasting ignore uncertainty in the parameter's value? How AlphaDev improved sorting algorithms? rev2023.6.29.43520. *g", DBL_DIG, 0 . *g", DBL_DIG, 0.00000037); printf("Here's one such string: %s\n", s); sprintf(s, "%. Hi guys, I have this part of code : struct __attribute__((packed)) DATASRUCT { uint16_t mac[6]; char receivedData[32]; char button[32]; float temp; float hum; float temp2; float hum2; uint8_t data; unsigned long time; } DataStruct; DataStruct.temp = 25.00; DataStruct.mac[6]={0x36,0x35,0x35,0x35,0x35,0x35}; but when i compile it gave me this error: cannot convert '<brace-enclosed initializer . GDPR: Can a city request deletion of all personal data that uses a certain domain for logins? You must pass the target parameter for Fmt by reference. Download at: http://www.antdb.net/download, choose X86 version under Open Euler How do you expect it to be converted? Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, The future of collective knowledge sharing. How to get pixel data from a UIImage (Cocoa Touch) or CGImage (Core Graphics)? Find centralized, trusted content and collaborate around the technologies you use most. I want to convert std::vector back to a float. yes reinterpret_cast is the way to handle such brute force type conversion. Making statements based on opinion; back them up with references or personal experience. Generally takes place when in an expression more than one data type is present. Was the phrase "The world is yours" used as an actual Pan American advertisement? To get a float that has the same binary representation (but, almost certainly different value) use *((float *)&val) (bear in mind the latter ASSUMES float is and unsigned are the same size and will not work as you describe for implementations that . do you have any good ideas? Share. Does a constant Radon-Nikodym derivative imply the measures are multiples of each other? Ive been Can anyone explain why floatVal = (float)val does not return the same result? Trying to convert string to byte array. I'm developing a project where I need to convert PCM 16-bits 2 channels sound into a IEEE Float 32-bits 2 channels. What I'm doing so far is I have an array of floats. Not the answer you're looking for? Is there any particular reason to only include 3 out of the 6 trigonometry functions? How one can establish that the Earth is round? How AlphaDev improved sorting algorithms? Additionally make sure length indicates the number of elments in pcmFrom and floatTo, and not the number of bytes allocated. Since we have integer promotion, we have enough precision to represent 285, so the (v > 255) test will be true and the value will be clamped to 255. It seems to work from a quick test but I'm not sure if it's safe. How to convert an unsigned int to a float? C++: Convert float [] to unsigned char* or BYTE*. On Subform1 I have a series of combo boxes whose names are Combo1, Combo2, Combo3, etc. myFunction ( (char *) myVarName) system August 1, 2012, 8:47am 3 That's not going to work if "myVarName" is a float! Convert short to int in C 41030 hits; Convert float to unsigned int in C 40400 hits; Convert long to float in C 39926 hits; Convert int to bool in C 37476 hits; Convert char* to wchar_t* in C 36184 hits; Convert long to char* in C 35780 hits; Convert int to wchar_t in C 34801 hits; Convert bool to char* in C 34466 hits; Convert unsigned char to . Join Bytes to post your question to a community of 472,480 software developers and data experts. Asking for help, clarification, or responding to other answers. Latex3 how to use content/value of predefined command in token list/string? The char array can now be accessed to get the byte values. What are the benefits of not using private military companies (PMCs) as China did? What do gun control advocates mean when they say "Owning a gun makes you more likely to be a victim of a violent crime."? In you case pcmFrom should have allocated length*2 bytes and floatTo needs room for length*4 bytes. Thank you for the informative post. Frozen core Stability Calculations in G09? Probably not, but I like to be verbose about type conversions. Oops, I've updated this. There's two things you can mean by saying conversion from signed to unsigned, you might mean that you wish the unsigned variable to contain the value of the signed variable modulo the maximum value of your unsigned type + 1. Yes, given your program's semantics, you can safely cast an array of signed chars to a pointer to unsigned char, with which you effectively say, this memory is not an array of signed chars, but an array of unsigned chars. (The final f just tells the value is of float type. I'm developing a project where I need to convert PCM 16-bits 2 channels sound into a IEEE Float 32-bits 2 channels. Note that in the case of ones' complement the unsigned value of 128 can actually not be represented in a signed char, since it ranges from -127 to 127, due to the -0 value. When the compiler converts an unsigned integer to a floating-point type, if the original value isn't representable exactly in the result type, the result is the next higher or lower representable value. Does a constant Radon-Nikodym derivative imply the measures are multiples of each other? rev2023.6.29.43520. Done by the compiler on its own, without any external trigger from the user. For example, (float)425 == 425.0f. Idiom for someone acting extremely out of character. Brinda soporte a clientes que utilizan Ethernet, GPIB, serial, USB y otros tipos de instrumentos. Is it legal to bill a company that made contact for a business proposal, then withdrew based on their policies that existed when they made contact? 1960s? FmtOut omits the target argument present in the other two functions. Not the answer you're looking for? 1) a function without a prototype 2) a variadic function, where the argument expression is one of the trailing arguments that are matched against the ellipsis parameter Each argument of integer type undergoes integer promotion (see below), and each argument of type float is implicitly converted to the type double I think you might be right but it wouldn't hurt to explain. How can I handle a daughter who says she doesn't want to stay with me more than one day? and no time to find out. #, Nov 13 '05
What I'm doing so far is I have an array of floats. What was the symbol used for 'one thousand' in Ancient Rome? What was the symbol used for 'one thousand' in Ancient Rome? How to convert it into float or double? Connect and share knowledge within a single location that is structured and easy to search. See Storage of basic types for information about the sizes of integral and floating-point types. Convert char* to int in C 64151 hits; Convert long to double in C 44967 hits; Convert unsigned long to int in C 43888 hits; Convert float to double in C 43157 hits; Convert short to int in C 41029 hits; Convert float to unsigned int in C 40392 hits; Convert long to float in C 39923 hits; Convert int to bool in C 37472 hits; Convert char* to . To learn more, see our tips on writing great answers. from A to B using explicit case conversion with no problem like "B = short Again, if your program assumes this, it should say so in the documentation, or check it at compile time (using a separate test program in the same project, for example). Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, The future of collective knowledge sharing, there's also endianness. Go to solution Convert a float to unsigned char BlueAnaconda Member 01-18-2017 02:41 AM Options Hello, I have a variable float type (example float a = 5.02) and I want to save the value into unsigned char. Do you realize, that CLAMP255 returns 0 for v < 0 and 255 for v >= 0? I am a newbie to Access (most programming for that matter). Convert from unsigned char array to float! - C / C++ Thanks for contributing an answer to Stack Overflow! Another, more elaborate way to convert a float value into a char string can be achieved using the following code below: how can I convert this string to a byte array of {107, 62, 139, 65} Making statements based on opinion; back them up with references or personal experience. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 585), Starting the Prompt Design Site: A New Home in our Stack Exchange Neighborhood, Temporary policy: Generative AI (e.g., ChatGPT) is banned. How Bloombergs engineers built a culture of knowledge sharing, Making computer science more humane at Carnegie Mellon (ep.
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