signed

Signed versus Unsigned Integers

由 ぐ巨炮叔叔 提交于 2019-11-26 09:10:44
Am I correct to say the difference between a signed and unsigned integer is: Unsigned can hold a larger positive value, and no negative value. Unsigned uses the leading bit as a part of the value, while the signed version uses the left-most-bit to identify if the number is positive or negative. signed integers can hold both positive and negative numbers. Any other differences? Greg Unsigned can hold a larger positive value, and no negative value. Yes. Unsigned uses the leading bit as a part of the value, while the signed version uses the left-most-bit to identify if the number is positive or

Why is 0 < -0x80000000?

由 风流意气都作罢 提交于 2019-11-26 06:11:36
问题 I have below a simple program: #include <stdio.h> #define INT32_MIN (-0x80000000) int main(void) { long long bal = 0; if(bal < INT32_MIN ) { printf(\"Failed!!!\"); } else { printf(\"Success!!!\"); } return 0; } The condition if(bal < INT32_MIN ) is always true. How is it possible? It works fine if I change the macro to: #define INT32_MIN (-2147483648L) Can anyone point out the issue? 回答1: This is quite subtle. Every integer literal in your program has a type. Which type it has is regulated by

Google map signed api key errors in Android

由 こ雲淡風輕ζ 提交于 2019-11-26 05:48:48
问题 When I switched from my debug map key to my signed map key my maps stop working. I get the following errors in logcat: 09-03 18:18:04.112: WARN/System.err(4073): IOException processing: 26 09-03 18:18:04.112: WARN/System.err(4073): java.io.IOException: Server returned: 3 09-03 18:18:04.112: WARN/System.err(4073): at android_maps_conflict_avoidance.com.google.googlenav.map.BaseTileRequest.readResponseData(BaseTileRequest.java:115) 09-03 18:18:04.112: WARN/System.err(4073): at android_maps

Why is a negative int greater than unsigned int? [duplicate]

由 荒凉一梦 提交于 2019-11-26 05:34:54
问题 This question already has an answer here: Comparison operation on unsigned and signed integers 7 answers int main(void) { unsigned int y = 10; int x = – 4; if (x > y) Printf(\"x is greater\"); else Printf(\"y is greater\"); getch(); return (0); } Output: x is greater I thought the output would be y is greater since it is unsigned. What\'s the reason behind this? 回答1: Because the int value is promoted to an unsigned int . specifically 0xFFFFFFFC on a 32-bit machine, which as an unsigned int is

Iteration over std::vector: unsigned vs signed index variable

由 本秂侑毒 提交于 2019-11-26 02:59:45
问题 What is the correct way of iterating over a vector in C++? Consider these two code fragments, this one works fine: for (unsigned i=0; i < polygon.size(); i++) { sum += polygon[i]; } and this one: for (int i=0; i < polygon.size(); i++) { sum += polygon[i]; } which generates warning: comparison between signed and unsigned integer expressions . I\'m new in the world of C++, so the unsigned variable looks a bit frightening to me and I know unsigned variables can be dangerous if not used correctly

Detecting signed overflow in C/C++

由 ╄→гoц情女王★ 提交于 2019-11-26 01:53:14
问题 At first glance, this question may seem like a duplicate of How to detect integer overflow?, however it is actually significantly different. I\'ve found that while detecting an unsigned integer overflow is pretty trivial, detecting a signed overflow in C/C++ is actually more difficult than most people think. The most obvious, yet naive, way to do it would be something like: int add(int lhs, int rhs) { int sum = lhs + rhs; if ((lhs >= 0 && sum < rhs) || (lhs < 0 && sum > rhs)) { /* an overflow

How to determine a Python variable&#39;s type?

由 安稳与你 提交于 2019-11-26 00:26:26
问题 How do I see the type of a variable whether it is unsigned 32 bit, signed 16 bit, etc.? How do I view it? 回答1: Python doesn't have the same types as C/C++, which appears to be your question. Try this: >>> i = 123 >>> type(i) <type 'int'> >>> type(i) is int True >>> i = 123456789L >>> type(i) <type 'long'> >>> type(i) is long True >>> i = 123.456 >>> type(i) <type 'float'> >>> type(i) is float True The distinction between int and long goes away in Python 3.0, though. 回答2: You may be looking

Signed/unsigned comparisons

由 不问归期 提交于 2019-11-26 00:09:48
问题 I\'m trying to understand why the following code doesn\'t issue a warning at the indicated place. //from limits.h #define UINT_MAX 0xffffffff /* maximum unsigned int value */ #define INT_MAX 2147483647 /* maximum (signed) int value */ /* = 0x7fffffff */ int a = INT_MAX; //_int64 a = INT_MAX; // makes all warnings go away unsigned int b = UINT_MAX; bool c = false; if(a < b) // warning C4018: \'<\' : signed/unsigned mismatch c = true; if(a > b) // warning C4018: \'<\' : signed/unsigned mismatch

What happens if I assign a negative value to an unsigned variable?

由 你离开我真会死。 提交于 2019-11-26 00:09:08
问题 I was curious to know what would happen if I assign a negative value to an unsigned variable. The code will look somewhat like this. unsigned int nVal = 0; nVal = -5; It didn\'t give me any compiler error. When I ran the program the nVal was assigned a strange value! Could it be that some 2\'s complement value gets assigned to nVal ? 回答1: For the official answer - Section 4.7 conv.integral "If the destination type is unsigned, the resulting value is the least unsigned integer congruent to the

Comparison operation on unsigned and signed integers

由 流过昼夜 提交于 2019-11-26 00:07:05
问题 See this code snippet int main() { unsigned int a = 1000; int b = -1; if (a>b) printf(\"A is BIG! %d\\n\", a-b); else printf(\"a is SMALL! %d\\n\", a-b); return 0; } This gives the output: a is SMALL: 1001 I don\'t understand what\'s happening here. How does the > operator work here? Why is \"a\" smaller than \"b\"? If it is indeed smaller, why do i get a positive number (1001) as the difference? 回答1: Binary operations between different integral types are performed within a "common" type
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