[英]print result using system calls
For my OS class, I need to print out the result of this matrix multiplication using only system calls. 对于我的OS类,我只需要使用系统调用就可以打印出矩阵乘法的结果。 Following my lecture notes, I wrote up this piece of code. 根据我的讲义,我编写了这段代码。 I use : 我用 :
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define N 1000
// Matrix
long long int A[N][N],B[N][N],R[N][N];
int main(int argc, char *argv[])
{
int x,y,z;
char str[100];
/* Matrix inicialization */
for(y=0;y<N;y++)
for(x=0;x<N;x++)
{
A[y][x]=x;
B[y][x]=y;
R[y][x]=0;
}
/* Matrix multiplication */
for(y=0;y<N;y++)
for(z=0;z<N;z++)
for(x=0;x<N;x++)
{
R[y][x]+= A[y][z] * B[z][x];
}
//System calls for printing the result
sprintf(str,"%lld\n",R);
write(1,str,strlen(str));
exit(0);
}
Now, it's printing a just a 14295680 in the console. 现在,它仅在控制台中打印14295680。 The professor gave us a file with machine code and it's printing 332833500, which seems more reasoneable. 教授给了我们一个带有机器代码的文件,它的打印内容为332833500,这似乎更加合理。
Thanks in advance. 提前致谢。
Edit: changed type on the printf call Edit2: fix R[N][N] 编辑:更改printf调用的类型编辑2:修复R [N] [N]
Just replace the sprintf value: 只需替换sprintf值:
sprintf(str,"%lld\n",R[N-1][N-1]); // = 332833500
write(1,str,strlen(str));
instead of 代替
sprintf(str,"%lld\n",R); // this is a pointer
write(1,str,strlen(str));
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