the c programming language 習題 第二章

exercise2.4

void squeeze(char s[],char t[]) { int i,j,k; int lens,lent; lens=strlen(s); lent=strlen(t); for(i=0,k=0;i<lens;i++) { for(j=0;j<lent;j++) if(s[i]==t[j]) break; if(j==lent) s[k++]=s[i]; } s[k]='/0'; } 

exercise2.5

int any(char s[],char t[]) { int i,j; for(i=0;s[i]!='/0';i++) for(j=0;t[j]!='/0';j++) if(s[i]==t[j]) return i; return -1; } 

exercise2.9

int bitcount(unsigned x) { int b; b=0; while(x) { x&=(x-1); b++; } return b; } 

exercise2.10

int lower(int c) { return (c>='A'&&c<='Z')?c+'a'-'A':c; }