C语言第五章作业.doc

5.1#include#include#includeint main(void) char s1000; printf(请输入字符串：); gets(s); int i=0; char ch; printf(请输入字符：); scanf(%c,&ch); int address; while(i1000) if(ch!=si) i+; else break; if(ch!=si) printf(无此项字符！n); else address=i+1; printf(第一次出现%c的地方是在字符串的第%d个位置n,ch,address); system(PAUSE); return 0; 运行结果：请输入字符串：abcdefg请输入字符：c第一次出现c的地方是在字符串的第3个位置请按任意键继续. . .运行结果：请输入字符串：abcdefg请输入字符：Z无此项字符！请按任意键继续. . .5.2#include#include#include#define MAXLINE 100double Atof(char s);int main(void) double sum; char lineMAXLINE; puts(Please input a digital string:); while(scanf(%s,line)0) sum=0; printf(t%lfn,sum+=Atof(line); puts(Please input another digital string:); system(PAUSE); return 0;double Atof(char s) double integer,decimal; int index; double power; int sign1,sign2; sign1=sign2=1; int i; for(i=0;isspace(si);i+) ; switch(si) case +: i+; break; case -: sign1=-1; i+; break; default: break; for(integer=0.0;isdigit(si);i+) integer=10.0*integer+(si-0); if(si=.) i+; for(decimal=0.0,power=10;isdigit(si);i+) decimal=decimal+(si-0)/power; power*=10; if(si=e | si=E) i+; switch(si) case +: i+; break; case -: sign2=-1; i+; break; default: break; for(index=0;isdigit(si);i+) index=10*index+(si-0); int j; if(sign2=-1) double p; for(j=0,p=1;jindex;j+) p/=10; return (integer+decimal)*p*sign1; else double p; for(j=0,p=1;jindex;j+) p*=10; return (integer+decimal)*p*sign1; 运行结果：Please input a digital string：2.3e423000.000000Please input an another digital st