[英]C program file read, reformat, write
我在while循環中遇到麻煩,如何獲取字符串,並且僅將名稱major和GPA顯示為列表。 另外,我在fgets
函數中需要幫助,因為每三行中的每一行都不同,所以我將如何在列表中顯示它們。 我將在while
循環中放入什么來使它起作用?
#include <stdio.h>
int main(void)
{
FILE *cfPtr;
FILE *ofp;
char name[20];
char major[3];
double gpa;
ofp = fopen("outputFile.txt","w");
fprintf(ofp,"Name\tMajor\tGPA\n");
if((cfPtr = fopen("inputFile.txt","r")) == NULL)
{
printf("This file could not be opened\n");
}
else
{
while (!feof(cfPtr))
{
fgets(name, 20, cfPtr );
//How to read the string and only display
//the name major and gpa?
//fprintf(ofp,"%s\t%s\t%f\n", name, major, gpa);
}
}
fclose(cfPtr);
fclose(ofp);
}
輸入文件為:
Name: John Milton
Major: EE
GPA: 3.98
Name: Karl Lewis
Major: CS
GPA: 3.6
Name: Homer Simpson
Major: CE
GPA: 4.0
我需要輸出文件為:
Name: Major: GPA:
John Milton EE 3.98
Karl Lewis CS 3.6
Homer Simpson CE 4.0
嗨,您可以這樣操作。如果必須使用fegts。
您應該聲明這些char數組,
char name[20];//enough long
char major[10];//enough long
char gpa[10];//enough long
char name_tag[7];//According to the "Name: "
char major_tag[8];//According to the "Major: "
char gpa_tag[6];//According to the "GPA: "
而while循環,
while (1)
{
if(fgets(name_tag,7,cfPtr) == NULL)
break;
if (feof(cfPtr))
{
break;
}
if(fgets(name, 20, cfPtr ) == NULL)
break;
if (name[strlen(name) - 1] == '\n')
{
name[strlen(name) - 1] = '\0';//remove '\n'
}
if(fgets(major_tag,8,cfPtr) == NULL)
break;
if(fgets(major,10,cfPtr) == NULL)
break;
if (major[strlen(major) - 1] == '\n')
{
major[strlen(major) - 1] = '\0';
}
if(fgets(gpa_tag,6,cfPtr) == NULL)
break;
if(fgets(gpa,10,cfPtr) == NULL)
break;
if (gpa[strlen(gpa) - 1] == '\n')
{
gpa[strlen(gpa) - 1] = '\0';
}
fprintf(ofp,"%s\t%s\t%s\n", name, major, gpa);
}
示例代碼:
#include <stdio.h>
typedef struct data {
char name[20];
char major[3];
double gpa;
} Data;
Data *fgets_data(Data *aData, FILE *fp){
if( fscanf(fp, "Name: %19[^\n]%*c", aData->name)==1 &&
fscanf(fp, "Major: %2s%*c", aData->major)==1 &&
fscanf(fp, "GPA: %lf%*c", &(aData->gpa))==1 )
return aData;
return NULL;//fail
}
void fputs_data(Data *aData, FILE *fp){
if(aData == NULL) //print caption
fprintf(fp, "%-20s%-8s%s\n",
"Name:", "Major:", "GPA:");
else
fprintf(fp, "%-20s%-8s%g\n",
aData->name, aData->major, aData->gpa);
}
int main(void){
FILE *cfPtr;
Data aData;
if((cfPtr = fopen("inputFile.txt","r")) == NULL){
fprintf(stderr, "This file could not be opened\n");
} else {
FILE *ofp = fopen("outputFile.txt","w");
fputs_data(NULL, ofp);//print fileld name
while (fgets_data(&aData, cfPtr)!=NULL)
fputs_data(&aData, ofp);
fclose(ofp);
fclose(cfPtr);
}
return 0;
}
我不會為您編寫代碼,但會幫助您某種程度地構建解決方案。
如果您查看輸入文件和預期的輸出格式,則可能如下所示:
open input and output files
while there are more lines in the input file
name = readline(); major = readline(); gpa = readline();
writeLine(name, major, gpa);
close files
現在,它只是一次找出每個步驟的代碼。
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