30 lines
404 B
C
30 lines
404 B
C
#include<unistd.h>
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#include<fcntl.h>
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int main(int argc,char**argv)
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{
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int fd=0;
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if(argc>1)
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{
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fd=open(argv[1],O_RDONLY);
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if(fd<0)
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{
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write(2,"failed to open file\n",20);
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fd=0;
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}
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}
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int c;
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while(read(fd,&c,1))
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{
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if(c>='a'&&c<='z')
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c=((c-'a')+13)%26+'a';
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else if(c>='A'&&c<='Z')
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c=((c-'A')+13)%26+'A';
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else if(c>='0'&&c<='9')
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c=((c-'0')+10)%10+'0';
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write(1,&c,1);
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}
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}
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