How can I find the error in this C program?

user_13992126 0
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I am learning data structures and pretty much new to C. I can't figure out what's causing the error in this function:

struct Student{
    int id;
    char name[30];
    double gpa;
    int ch;
};

void displayStudents() {
 struct Student students[10]={
    {1, ahmed ,3.6,43},
    {2, mohamed, 3.2, 40},
    {3,hassan, 3.0, 41},
    {4, hossam, 2.5, 35},
    {5, hany, 2.3, 32},
    {6, hala, 2.7, 37},
    {7, hana, 2.8, 33},
    {8, ramadan,3.8,46},
    {9, sameh,3.7,43},
    {10, nour,3.3,42}
 };

  for(int i=0; i<9; i++) {
    printf("%d,%s,%lf, %d", students[i].id, students[i].name, students[i].gpa, students[i].ch);
  }

}

It gives me those errors when compiling:

||=== Build: Debug in Data Structure Project (compiler: GNU GCC Compiler) ===|
C:\Users\Shiko\Desktop\C Tutorials\Data structure project\main.c||In function 'displayStudents':|
C:\Users\Shiko\Desktop\C Tutorials\Data structure project\main.c|94|error: 'ahmed' undeclared (first use in this function)|
C:\Users\Shiko\Desktop\C Tutorials\Data structure project\main.c|94|note: each undeclared identifier is reported only once for each function it appears in|
C:\Users\Shiko\Desktop\C Tutorials\Data structure project\main.c|95|error: 'mohamed' undeclared (first use in this function)|
C:\Users\Shiko\Desktop\C Tutorials\Data structure project\main.c|96|error: 'hassan' undeclared (first use in this function)|
C:\Users\Shiko\Desktop\C Tutorials\Data structure project\main.c|97|error: 'hossam' undeclared (first use in this function)|
C:\Users\Shiko\Desktop\C Tutorials\Data structure project\main.c|98|error: 'hany' undeclared (first use in this function)|
C:\Users\Shiko\Desktop\C Tutorials\Data structure project\main.c|99|error: 'hala' undeclared (first use in this function)|
C:\Users\Shiko\Desktop\C Tutorials\Data structure project\main.c|100|error: 'hana' undeclared (first use in this function)|
C:\Users\Shiko\Desktop\C Tutorials\Data structure project\main.c|101|error: 'ramadan' undeclared (first use in this function)|
C:\Users\Shiko\Desktop\C Tutorials\Data structure project\main.c|102|error: 'sameh' undeclared (first use in this function)|
C:\Users\Shiko\Desktop\C Tutorials\Data structure project\main.c|103|error: 'nour' undeclared (first use in this function)|
||=== Build failed: 10 error(s), 0 warning(s) (0 minute(s), 0 second(s)) ===|

I suspect the problem might be in the parameters of the function displayStudents(). I don't know what to type there, I searched far and wide and couldn't find anything.

data-structures c
3 Answers

You have to use "" for a string

void displayStudents() {
 struct Student students[10]={
    {1, "ahmed" ,3.6,43},
    {2, "mohamed", 3.2, 40},
    {3, "hassan", 3.0, 41},
    {4, "hossam", 2.5, 35},
    {5, "hany", 2.3, 32},
    {6, "hala", 2.7, 37},
    {7, "hana", 2.8, 33},
    {8, "ramadan",3.8,46},
    {9, "sameh",3.7,43},
    {10, "nour",3.3,42}
 };

  for(int i=0; i<9; i++) {
    printf("%d,%s,%lf, %d", students[i].id, students[i].name, students[i].gpa, students[i].ch);
  }

}

If you want to see your function, just call that function.

int main(void) {
  displayStudents();
  return 0;
}

Output:

1,ahmed,3.600000, 432,mohamed,3.200000, 403,hassan,3.000000, 414,hossam,2.500000, 355,hany,2.300000, 326,hala,2.700000, 377,hana,2.800000, 338,ramadan,3.800000, 469,sameh,3.700000, 43
user_104296210

There is the error about using strings in C. Your code would work if you delfine enumeration type declaring all the used personal names/surnames. You should also change the definition of structure. Otherwise, strings in C require more work, e.g. memory allocation.

EDIT: in your code - you define structure using the initialization block - it is enough to add quotes. However, this is not a general solution!

user_10226570

In most of the languages, chars and strings are initialised in quotes, single or double. In C, there is no concept of string, rather there is char array. when a char is declared, then the value inside it is initialised in single quotes, (when the value is a single character), but when char array or pointer to char is used, for the purpose of string, then , the value inside it is initialised using double quotes. Also, its a good habit to use typedef in struct, it makes the code more readable. you may change to

typedef struct Std{ //any random name
    int id;
    char name[30];
    double gpa;
    int ch;
    }Student;

void displayStudents() {

Student students[10]={ //no need to write struct everytime any more

{1, "ahmed" ,3.6,43},
{2, "mohamed", 3.2, 40},
{3,"hassan", 3.0, 41},
{4, "hossam", 2.5, 35},
{5, "hany", 2.3, 32},
{6, "hala", 2.7, 37},
{7, "hana", 2.8, 33},
{8, "ramadan",3.8,46},
{9, "sameh",3.7,43},
{10, "nour",3.3,42}
};
user_128630760
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