c

问题 This question already has answers here : Closed 9 years ago . Possible Duplicate: what is the difference between #include <filename> and #include “filename” I would like to know what's the difference between #include "stdio.h" and #include <stdio.h> 回答1: Use <whatever> for system headers, and "whatever" for your own headers. The difference is that when it's enclosed in quotes, the compiler will look in the local directory, but with <> , it won't. If you want to get technical, the C standard

问题 This question already has answers here : Closed 9 years ago . Possible Duplicate: what is the difference between #include <filename> and #include “filename” I would like to know what's the difference between #include "stdio.h" and #include <stdio.h> 回答1: Use <whatever> for system headers, and "whatever" for your own headers. The difference is that when it's enclosed in quotes, the compiler will look in the local directory, but with <> , it won't. If you want to get technical, the C standard

问题 The task is very simple, writting a seqence of integer variable to memory: Original code: for (size_t i=0; i<1000*1000*1000; ++i) { data[i]=i; }; Parallelized code: size_t stepsize=len/N; #pragma omp parallel num_threads(N) { int threadIdx=omp_get_thread_num(); size_t istart=stepsize*threadIdx; size_t iend=threadIdx==N-1?len:istart+stepsize; #pragma simd for (size_t i=istart; i<iend; ++i) x[i]=i; }; The performance sucks, it takes 1.6 sec to writing 1G uint64 variables (which is equal to 5GB

问题 Related questions How can I detect the operating system in C/C++? How can I find out what operating system I am running under in GCC or in ANSI C? I'd be fine If I can know if I'm running on POSIX. UPDATE: It doesn't make a difference to me whether it is at compile time or run time. I'm using this in a debug routine, so performance isn't that important. I'm looking for the path separator. Windows & Unix/Linux/BSD would be fine. And, I'm trying to find the basename on a path. I found some

问题 I wish to know which of these two options is the more secure one to use: #define MAXLEN 255 char buff[MAXLEN + 1] sprintf(buff, "%.*s", MAXLEN, name) snprintf(buff, MAXLEN, "%s", name) My understanding is that both are same. Please suggest. 回答1: The two expressions you gave are not equivalent: sprintf takes no argument specifying the maximum number of bytes to write; it simply takes a destination buffer, a format string, and a bunch of arguments. Therefore, it may write more bytes than your

问题 I wish to know which of these two options is the more secure one to use: #define MAXLEN 255 char buff[MAXLEN + 1] sprintf(buff, "%.*s", MAXLEN, name) snprintf(buff, MAXLEN, "%s", name) My understanding is that both are same. Please suggest. 回答1: The two expressions you gave are not equivalent: sprintf takes no argument specifying the maximum number of bytes to write; it simply takes a destination buffer, a format string, and a bunch of arguments. Therefore, it may write more bytes than your

问题 Question: void swap (int v[], int k) { int temp; temp = v[k]; v[k] = v[k+1]; v[k+1] = temp; } My question is why does int v[] get added $t1 ? (whoever did this didn't even comment it so I'm assuming $a0 is v[] and $a1 is k ). Answer in mips: swap: sll $t1, $a1, 2 add $t1, $a0, $t1 lw $t0, 0($t1) lw $t2, 4($t1) sw $t2, 0($t1) sw $t0, 4($t1) jr $ra I know this is used to swap variables but what is it doing here, why is it adding v[] with k ? Isn't v[] a array of declared variables, how can you

问题 EDIT: After re-writing my code in my IDE, for the 8th time today, I have made rookie mistake of giving my inputs a false data type, that has been fixed but my outputs still are incorrect. Details about my goal: When making change, odds are you want to minimize the number of coins you’re dispensing for each customer. Well, suppose that a cashier owes a customer some change and in that cashier’s drawer are quarters (25¢), dimes (10¢), nickels (5¢), and pennies (1¢). The problem to be solved is

问题 c performance profiling time-limiting Details of the purpose of writing the program is given on the link : https://www.spoj.com/problems/CRCLE_UI/ And the error Time limit exceeded #include<stdio.h> const int mod=1000000007; int cal(int a, int b){ long long x=1,y=a; while(b){ if(b&1)x=x*y; if(x>=mod)x=x-(x/mod)*mod; y=y*y; if(y>=mod)y=y-(y/mod)*mod; b>>=1; } return x; } int main(){ int t, n, k; long long ans,a1; for(scanf("%d",&t);t--;){ scanf("%d %d", &n, &k);;t--; k--; if(k>=mod)k%=mod; ans

问题 This question already has answers here : Returning an array using C (8 answers) Closed last month . I was trying to append two const char* from a function but it returns (null) . What should I do now? I'm working in VS Code on Ubuntu 20.04 using GCC Compiler v9.3.0. Code #include <string.h> #include <stdio.h> char *JoinChars(const char *a, const char *b) { char buffer[strlen(a) + strlen(b) + 1]; strcpy(buffer, a); strcat(buffer, b); return buffer; } int main() { const char *b1 = "Hello\t";