1. Problem description
During the development of embedded Linux, compile and report the following errors
src/util/Vector.c:94:9: error: ‘for’ loop initial declarations are only allowed in C99 mode
for (int j = V->length++; j > i; j--)
^
src/util/Vector.c:94:9: note: use option -std=c99 or -std=gnu99 to compile your code
src/util/Vector.c: In function ‘Vector_remove’:
src/util/Vector.c:123:9: error: ‘for’ loop initial declarations are only allowed in C99 mode
for (int j = i; j < V->length; j++)
^2. Problem analysis
GCC compilation is based on compilation lower than C99 standard. Defining variables within a for loop is not allowed in standards lower than C99.
3. Solution
Method 1
Modify code
int j;
for (j = i; j < V->length; j++)Method 2
GCC specifies compiling using the C99 standard
gcc -std=c99Method 3
Specify the C99 standard for compilation in makefile
CFLAGS += -std=c99