这是我的代码：
#include <stdio.h>
#include <string.h>
#define numlines 2201
#define linelen 99
typedef struct
{
char class[99];
char age[99];
char gender[99];
char survived[99];
} Passenger;
int cmpStruct(Passenger pa, Passenger Query);
Passenger lineToStruct(char line[]);
Passenger queryToStruct(char line[]);
int findMyChar(char str[], int size, int start, char ch);
int Computation(Passenger Query, Passenger allPassengers[]);
int main(void)
{
FILE *fp;
fp = fopen("Titanic.txt", "r");
if (fp == NULL)
{
printf("Error opening file %s, \n", "Titanic.txt");
return -1;
}
Passenger allPassengers[numlines];
int n = 0;
while(1)
{
char line[numlines];
if (fgets(line, linelen, fp) == NULL)
{
break;
}
allPassengers[n] = lineToStruct(line);
n++;
}
fclose(fp);
Passenger Query;
char query[99];
while (1)
{
printf("\nType 1 for query, or 0 to quit: ");
int begin;
scanf("%d",&begin);
if (begin == 0)
{
printf("Bye Bye!\n\n");
return 0;
}
while(1)
{
printf("Type in the query that you want to know");
printf(" sample query is: class=first,age=adult,gender=male \n");
scanf("%s", &query);
break;
}
int iteration1;
int iteration2;
int iteration3;
if(query == "all")
{
for(iteration1=1; iteration1<=4;iteration1++)
{
if(iteration1==1)
{
strcpy(Query.class, "first");
}
if(iteration1==2)
{
strcpy(Query.class, "second");
}
if(iteration1==3)
{
strcpy(Query.class, "third");
}
if(iteration1==4)
{
strcpy(Query.class, "crew");
}
for(iteration2=1; iteration2<=2;iteration2++)
{
if(iteration2==1)
{
strcpy(Query.age, "adult");
}
if(iteration2==2)
{
strcpy(Query.age, "child");
}
for(iteration3=1; iteration3<=2;iteration3++)
{
if(iteration3==1)
{
strcpy(Query.gender, "male");
}
if(iteration3==2)
{
strcpy(Query.gender, "female");
}
Computation(Query, allPassengers);
}
}
}
}
else
{
Query = queryToStruct(query);
float totalPassengers = 0;
float survived = 0;
float percentage;
int i;
for(i=0;i<numlines;i++)
{
if (cmpStruct(allPassengers[i],Query)==0)
{
totalPassengers++;
if (strcmp(allPassengers[i].survived,"yes")==0)
{
survived++;
if (cmpStruct(allPassengers[i],Query)==1)
{
printf("error");
break;
}
}
}
}
percentage = survived/totalPassengers*100;
printf("\nResults:\n");
printf("\nClass = %s\nAge = %s\nGender = %s\n\n",Query.class,Query.age,Query.gender);
if (totalPassengers == 0)
{
printf("There was an error within the query\n");
}
else
{
printf("%.0f passengers are in the query (of 2201), %.0f of them survived\n",totalPassengers,survived);
}
if (totalPassengers != 0)
{
printf("Chance of survival is %.1f%c\n",percentage,'%');
}
}
}
}
int findMyChar(char str[], int size, int start, char ch)
{
int i;
for(i=start;i<size;i++)
{
if(str[i]==ch)
{
return i;
}
}
return -1;
}
Passenger lineToStruct(char line[])
{
Passenger passengerL;
int classInd = findMyChar(line, 99, 0, '=');
char class = line[classInd+1];
switch (class)
{
case 'f':
strcpy(passengerL.class, "first");
break;
case 's':
strcpy(passengerL.class, "second");
break;
case 't':
strcpy(passengerL.class, "third");
break;
case 'c':
strcpy(passengerL.class, "crew");
break;
case 'a':
strcpy(passengerL.class, "any");
break;
}
line[classInd] = '!';
int ageInd = findMyChar(line, 99, 0, '=');
char age = line[ageInd+2];
switch (age)
{
case 'd':
strcpy(passengerL.age, "adult");
break;
case 'h':
strcpy(passengerL.age, "child");
break;
case 'n':
strcpy(passengerL.age, "any");
break;
}
line[ageInd]= '!';
int genderInd = findMyChar(line, 99, 0, '=');
char gender = line[genderInd+3];
switch (gender)
{
case 'l':
strcpy(passengerL.gender, "male");
break;
case 'm':
strcpy(passengerL.gender, "female");
break;
case 'y':
strcpy(passengerL.gender, "any");
break;
}
line[genderInd] = '!';
int survivedInd = findMyChar(line, 99, 0, '=');
char survived = line[survivedInd+1];
switch (survived)
{
case 'y':
strcpy(passengerL.survived, "yes");
break;
case 'n':
strcpy(passengerL.survived, "no");
break;
}
line[classInd] = '=';
line[ageInd] = '=';
line[genderInd] = '=';
return passengerL;
}
Passenger queryToStruct(char line[])
{
Passenger passengerQ;
int classInd = findMyChar(line, 99, 0, '=');
char class = line[classInd+1];
switch (class)
{
case 'f':
strcpy(passengerQ.class, "first");
break;
case 's':
strcpy(passengerQ.class, "second");
break;
case 't':
strcpy(passengerQ.class, "third");
break;
case 'c':
strcpy(passengerQ.class, "crew");
break;
case 'a':
strcpy(passengerQ.class, "any");
break;
}
line[classInd]= '!';
int ageInd = findMyChar(line, 99, 0, '=');
char age = line[ageInd+2];
switch (age)
{
case 'd':
strcpy(passengerQ.age, "adult");
break;
case 'h':
strcpy(passengerQ.age, "child");
break;
case 'n':
strcpy(passengerQ.age, "any");
break;
}
line[ageInd] = '!';
int genderInd = findMyChar(line, 99, 0, '=');
char gender = line[genderInd+3];
switch (gender)
{
case 'l':
strcpy(passengerQ.gender, "male");
break;
case 'm':
strcpy(passengerQ.gender, "female");
break;
case 'y':
strcpy(passengerQ.gender, "any");
break;
}
line[classInd] = '=';
line[ageInd] = '=';
return passengerQ;
}
int cmpStruct(Passenger pa, Passenger Query)
{
if (strcmp(Query.class, "any") != 0 && strcmp(Query.class, pa.class) != 0)
return 1;
if (strcmp(Query.age, "any") != 0 && strcmp(Query.age, pa.age) != 0)
return 1;
if (strcmp(Query.gender, "any") != 0 && strcmp(Query.gender, pa.gender) != 0)
return 1;
return 0;
}
int Computation(Passenger Query, Passenger allPassengers[])
{
int totalPassengers = 0;
int survived = 0;
float percentage;
int i;
for(i=0;i<numlines;i++)
{
if (cmpStruct(allPassengers[i],Query)==0)
{
totalPassengers++;
if (strcmp(allPassengers[i].survived,"yes")==0)
{
survived++;
if (cmpStruct(allPassengers[i],Query)==1)
{
printf("error");
break;
}
}
}
}
percentage = survived/totalPassengers*100;
printf("\nResults:\n");
printf("\nClass = %s\nAge = %s\nGender = %s\n\n",Query.class,Query.age,Query.gender);
if (totalPassengers == 0)
{
printf("There was an error within the query\n");
}
else
{
printf("%.0f passengers are in the query (of 2201), %.0f of them survived\n",totalPassengers,survived);
}
if (totalPassengers != 0)
{
printf("Chance of survival is %.1f%c\n",percentage,'%');
}
}
该程序的目标是使用给定的文本文件（Titanic.txt）并打印出任何给定查询的生存机会。可以输入查询，如：
类=第一，年龄=儿童，gender = male的
类=船员，年龄=成人，性别=女性
类=任何，年龄=成人，性别=任何
所有
等
可能的班级是第一，第二，第三和船员，可能的年龄是成人或儿童，可能的性别是男性和女性。
所以，我遇到的问题是当我输入'all'时我的程序没有产生结果。这在我给出的输出图中描述。我认为错误是在我的主循环中使用的for循环中，或者是在我程序结束时使用的计算函数中。
答案 0 :(得分：1)
主要问题
if(query == "all")
错了。它比较了两个指针。它没有比较字符串。你需要使用：
if( strcmp(query, "all") == 0 )
其他错误
在使用-Wall标志进行编译时，我从gcc收到以下消息。
soc.c: In function ‘main’:
soc.c:83:10: warning: format ‘%s’ expects argument of type ‘char *’, but argument 2 has type ‘char (*)[99]’ [-Wformat=]
scanf("%s", &query);
^
soc.c:91:16: warning: comparison with string literal results in unspecified behavior [-Waddress]
if(query == "all")
^
soc.c: In function ‘Computation’:
soc.c:439:7: warning: format ‘%f’ expects argument of type ‘double’, but argument 2 has type ‘int’ [-Wformat=]
printf("%.0f passengers are in the query (of 2201), %.0f of them survived\n",totalPassengers,survived);
^
soc.c:439:7: warning: format ‘%f’ expects argument of type ‘double’, but argument 3 has type ‘int’ [-Wformat=]
soc.c:447:1: warning: control reaches end of non-void function [-Wreturn-type]
}
^
可以通过更改
来修复第一个scanf("%s", &query);
到
scanf("%s", query);
^^^ Remove the &
第二个是主要问题。
可以使用格式字符串中的%d代替%.0f修复第三个。
可以通过将Computation的返回类型更改为void来修复第四个问题。由于您没有从函数返回任何内容，并且调用它的位置不期望返回值，因此将返回类型更改为void似乎是有意义的。
还有一个错误未被编译器捕获。它是以下一行：
percentage = survived/totalPassengers*100;
由于整数除法，这将导致0被分配到percentage。将其更改为：
percentage = 1.0*survived/totalPassengers*100;
或
percentage = 100.0*survived/totalPassengers;